The Killer Sudoku Of Prime Numbers

[Music] thank you hello and welcome to Friday's edition of cracking the cryptic and we're going for the from the sublime to the ridiculous today yesterday zetamath's puzzle Buffet featured I think the longest rule set that we've ever we've ever featured on the channel today's puzzle which is called Primal Instinct by agent features what must be one of the shortest rule sets on the puzzle um and Pat I'll just tell you what the rules are normal Sudoku rules apply and digits in cages cannot repeat and must sum to a prime number and then there's an explanatory sentence which says for the avoidance of Doubt one is not a prime number and that's all of the rules absolutely fantastic stuff a slightly daunting grid with no given digits and it's actually not fully covered in cages either um but we've had this one recommended to us a few times over the last days and the some of the comments have been but just ridiculously good what what one yeah someone said that this is frankly the best Sudoku puzzle they have ever seen so if you like your prime numbers I think you might enjoy this one um now I've got some news for you before before we kick off today uh which bit of news shall I do first I'll do I'll do the word related news so some of you may know that Mark does um a Wordle in a minute uh that's a video that appears on the channel as a YouTube short normally every day it's also on Tick Tock and Instagram for those of you who frequent such places um and Mark does Wordle on hard mode which means that when you make a guess you have to use any positive information you get from that guest in any subsequent guesses so you can't do you know any of the old tricks about guessing sequences of five different letters each time in order to hone in on the actual letters used anyway Mark is very good at this but you may if you want to if you have a bit of Shard and Freud or in your personality you may want to want to have a look at the video that we released earlier on today which was not a YouTube short because indeed it is about six minutes long and it features Mark getting progressively more and more baffled and it's just such a rare thing to see that I think many of you will enjoy I'll try and remember to put a link on the screen now for those of you who have that Chardon Freud in your personalities you may also enjoy enjoy watching me struggle um we did a Times crossword masterclass in inverted commas today I solved the Times crossword I did solve it um I should maybe that's no I mean that's probably not worth a spoiler is it I did I do solve it in the end but I have to say the last entry in particular uh I have a lot well I have a great deal of difficulty with um so if you want to see me really quite baffled um you can watch that video I'll try and remember to put a link to that on the screen um now what else can I tell you about let's let's um let's do some birthday announcements I'm I'm very nearly caught up with my birthday announcements after my brief holiday last week um so JC you have turned 54 today I believe I think it's today actually so this is not a late one um over there in Virginia and I know this because your wife Jennifer wrote to us and I hope I've got the day right JC and I hope you have chocolate cake um not a birthday but Macy has just graduated with a first class degree well done Macy uh and Macy enjoys killer Sudoku so this this should be right up your street Macy and I know that I know all this because your boyfriend Stephen wrote to us and wanted to let us know how proud he is of you for achieving that degree and well as as he should be um I think this is the Constructor Nordy for the next birthday uh naughty is it your birthday today maybe we should have we should have reached out for a naughty puzzle but anyway gotta hello uh wrote to us and said that you'd appreciate a shout out um next Patricia in Shrewsbury um the different part of England than I'm in but not not that far away um now Patricia is a grandmother of a seven and nearly nine-year-old um who I think are in Germany actually um but Patricia happy birthday and this this message is from Innis Neil Sakura and Lily and I think so secure it must be your birthday soon happy birthday for that um Rich turns 28 today which is indeed the 28th of the month so a golden birthday hope you have chocolate cake to celebrate rich and and then oh a late birthday Scott on the 19th over there in Massachusetts um I think most of your family are actually near Saratoga um but your daughter Sarah wrote to us and described you as an amazing dad and she couldn't ask for a better father um which is a rather nice thing to hear I hope you had a great birthday and Sarah did in fact share with me something quite wonderful which I'm going to share with you this which is her art about our monthly reward uh the planet Suite which was our Sudoku hunt over on patreon for last month and look Maverick is flying through the planets isn't that absolutely brilliant so Sarah thank you very much for sharing that with me I'm most impressed I love I love fan art when we get it it really does uh tickles me pink um and right and that brings us nicely on to patreon where I have an apology to make um we we left off some names yesterday uh from the role of Honor that we did because the way we the way we construct the roles of honor is we search for the for the answer in our in our Gmail account um now unfortunately some people left out the spaces in their answers um and therefore we missed those out yesterday so many apologies um and what we thought we should do because those people were also therefore left out of the prize draw is we're going to give another prize so we drew that out and Chase Phillips well done you have won the sort of the other prize now for this month's monthly reward however the crack in the cryptic so congratulations we'll run another roll of Honor it's much shorter roll of Honor it's about 30 seconds long at the end of this video and don't forget if you are into Sudoku hands and why wouldn't you be first of August it's only a few days away and we have a brand new hunt coming up to collaboration between cracking the cryptic and glum hippo about tennis no less and that is looking in fine shape indeed so we we know you're gonna like that so if you want to if you want to get involved in that competition do join us um do join us before the first a couple of bucks a month and most people would tell you who who are patrons that it is the best value entertainment on this planet um certainly per hour per hour of enjoyment you get um anyway that's all that's all the messages let's have a look at Primal Instinct I've done the rules I'm not gonna I don't have to do the rules again do I so let's see what agent who is a Constructor I really really like has gone in store for us the way to play is to click the link under the video as usual but now I get to play Let's get cracking so I'm gonna have to have my prime number brain on today aren't I and probably Avail myself mightily of the secret um yes yes okay I can I mean I don't know if this is how you're meant to go about doing this puzzle but I can tell you something about that digit so maybe we should start by me telling you the secret now the secret is something I only tell my very favorite people but if you are prepared to watch a man solve a Sudoku about prime numbers by a fantastic Constructor and spend your Friday night in such fashion then I you are absolutely one of my favorite people you and I would get on mightily finally at a party um now the Sudoku Secret is that any complete row any complete column and any complete box of a Sudoku contains the digits one to nine once each because of the rules of Sudoku and if you add up those numbers you get 45 now 45 is an interesting number because it's odd now let's think about how this box might work when we're if these two cells have to add up to a prime number there's only one even prime number and that's two and you can't make a Sudoku Domino add up to two without repeating a digit so that's not going to work so we know that each of these dominoes adds up to an odd number and there are four such dominoes aren't there now for add four odd numbers together you get an even number but 45 is an odd number so that digit must be you've guessed it that's odd in fact this might be a parity shading puzzle um will will mull that over yeah okay because look can't I extend that logic here again each of these cages must add to an odd number but if that cage adds up to an odd number overall and that is itself an odd number those digits must add up to an even number which means that these eight cells add up to an even number because two odd numbers which that's odd that's odd plus that even we must be on an even total now so that's also odd together so we now know these three digits add up to an even number um okay no this might I might have run out of cleverness now oh dear dear dear oh no right I can do the same thing in row six odd plus odd plus odd is odd we need to retain that odd parity so that is even now that therefore is definitely odd because that Domino must add up to an odd number overall oh I like this so far I do like parity puzzles um oh oh sorry no okay uh there's the single digit cages here none of these can be a one um because one is not a prime number oh ah sorry I forgot one of them could be a two oops I was about to say these half don't these have to be three five and seven but I forgot that two was Prime and could go in a cage if that cage is a one Cell cage oh um ah okay no we can do we can do a different well it's a similar logic but different on this box overall that's an odd number isn't it and that's an odd number this this cage so at the moment we're on an even total which means these three digits have to add up to an odd total which means that they uh well if one of them was even there's only one even prime so the other two would be odd and they would add up to an even total so 2 is not involved in these three cells and therefore because nine is not prime we must be looking at three five and seven that's the only three single digit primes that are not two that's huge isn't it that's going to be huge now right so one a nine now have to be allocated one of the one of those digits has to go into this cage and one of them has to go into this cage because we need to ensure that each cage individually has an odd total and to achieve an odd total you will need an odd number trust me you can add as many even digits as you like and you won't get to an odd number right okay so if we had a one here these two digits would both be even but it could be something like two and four couldn't they that would be easier four and eight uh okay there are options uh what about with nine if we go nine this was a nine 924 doesn't work 926 does oh 928 does oh six six eight nine also uh okay all right so this is probably not where we look next there seem to be lots of ways we can make totals that add up to prime numbers using one and nine and even numbers only this must be not this can't be relevant um oh what about that row that though is a bit of a naughty digit isn't it that's a one Cell cage but we don't know it's we don't know it's parity it could be two again so I was thinking I could get this digit but I don't think I can until I know whether that's odd or even oh what about well actually I'm wondering I'm actually switching Tech now wondering about geometry about this cage this is one of these cages that we see in killer Sudoku or don't see it often but but it has a a very understood effect to my brain at least which is that it causes roping what do I mean by roping well what I mean is that because ah I'll just had another thought but okay we'll come back to that I'll do the roping first I've had another thought um but um yes what what is roping well the question is or the effect arises because you can't repeat digits in a cage so these three cells here we can ask where they live in box eight and they can't live there because they'd repeat in this cage and they can't live there because they'd repeat in their row so they must live there which means they live there and once you get that effect you can then ask where those digits go in box seven and they can't be green Green's already appeared in box eight so they must go up here which means they go there by Sudoku and we can we can create these lovely and strange ice cream flavors like this right so now well now I'm no doubt we'll be up well no I'm not in no doubt but I'm sure we can do something possibly um or we might have to use the other thing I noticed hang on hang on hang on hang on can we deduce anything sensible from this I know that I know these three digits are definitely adding up to an odd number oh sorry I'm not spotting in that's really weird actually I'm slightly surprised about that I think I have a horrible feeling I'm missing something terribly obvious the other the other thought I had just to let you know what that is is to look at those nine cells together as a package because these two Corner cages here they see the entirety of that seven Cell cage you can't I mean what do I mean by C what I mean is let's imagine this digit was a five can that five appear anywhere in that cage well clearly not because it would rule five it would see the five either in its box or in its row so these two digits and these seven digits must be the nine Sudoku digits altogether but yes okay but I know that that the total of these seven digits is odd so so in order if this is nine Sudoku digits which we now add up to the secret which is 45 then these two cells must add up to an even number which means they must have the same parity and because there is only one one cell number that could be a prime that is um even we can't if we put two in one of these we can't find a second even number to put into that would be prime both of these are odd neither of them are one neither of them are nine so these are three five and seven and that's giving us a three five seven tripling column one that's quite beautiful isn't it it's really really fascinating to me that you can actually start to deduce things from just a whole bunch of cages um now now what I'm tempted to do foreign well yeah okay so we can ask a question like oh my maths was wrong no no it's not wrong my math is not no my math is wrong 8 No Mercy is wrong oh oh no well all right I'm gonna change it around my maths was wrong but I'm going to change it round so my math becomes right again okay could those two digits be three and seven no because if this is three and seven we know what the sum of this cage is it's 45 minus 3 minus seven which is 35 and 35 is not prime so that cannot this cannot be a three seven pair now can it be a five seven pair no because five and seven add up to 12 which would mean this was a 33 cage and 33 is not prime either so this has to be three and five is the only thing it can be and three and five is the number I first thought of which I thought didn't work but actually does because that makes this cage add up to 37 and 37 is prime and now right now I've got a 357 triple that's slightly different in column one in the sense that the seven in this triple is definitely at the in this Domino here so that's not a seven and now I've got a 3 5 pair in column two and and okay so now I know there's a three and a five in here and a three and a five in here three and five add up to eight so I've got right so this this needs another odd digit doesn't it because we need to change the parity of this this cage in order for this cage to add up to an odd number overall you can't add one to it because uh 9 is not Prime if we add 7 to it fifteen is not Prime yeah so that's got to be that's got to be three five nine it's the only way we can and now now that's become a nine this is absolutely incredible and the wonderful thing about it is it's so far it's not that you know it's not monstrously hard is it we can actually we can at least do it um and we're gonna probably get a three in the corner um come on right now what does that mean ah I'm not sure yet though the these two cells are both odd so they add up to an even number so this is a one or a seven because it must be odd to make that cage uh have a prime total now um okay now I'm not spotting anything at all which is a bit embarrassing can I can I revisit row seven now if that's odd yes yes oh that's so so pretty it's so pretty right I can I know what that digit is now I actually know exactly what it is and that will give you a clue as to how I um because if we look at the parity now of this row that's odd those three add up to odd numbers these four add up to odd numbers so these eight cells add up to an odd total so that's three odd numbers we're adding up so that in order to retain the parity of 45 for the row which is odd needs to be even so that's got to be two it's the only possibility so now this cage has got all the all the other even digits in it it's got four six eight and either one or seven and four six and eight add up to eighteen and if you add seven to eighteen you get 25 and 25 is not prime so you must add one to it and you get 19 which is Prime and that gives us this digit which is now a seven uh this is just it's beautiful absolutely beautiful so now there's twos and sevens in green look two and seven two and seven um hang on a minute let me think about that does that help us with anything at all seven here can we get this sorted out I doubt it although it's not three and five here because three and five would make this cage add up to 15 which won't work so there is definitely a nine in this Domino and that's not nine um let's see if we can do any better than that so if we do nine and three we get set we get 19 wouldn't we which is fine and if we do nine and five four no 21 doesn't work nine five seven doesn't work that is 21 yeah so we can't put five in there so five goes there and we get a three nine pair and this adds up to 19 which is fine so now right now look we can do some some deletions up here not many deletions though um don't know what to do now we've got uh okay what am I meant to do now so far as well what I've Loved is that everything it's been very linear so I think what I need to do here is I need to just spend a moment or two if I can't find an obvious Next Step I'm probably missing something um foreign I'm sorry let me just mull this over so I know Green has got one of one four six and eight I've got to make this cage this has got to add up to a prime number and the corner digit oh I don't know I'm not sure how to think about this actually can that be 2 7 that would give us 21 20 no that right that corner digit is two or seven I think um because by Sudoku I know there's a two and a seven down here and if that two seven go here then an S my maths is wrong which it could be those squares add up to 21. and that would mean these squares are up to 24 which is most certainly not prime so I think we've got to put two or seven here but does that I feel like there's a parody thing going on there or does it know it's going to depend on what the other digit is here which could be either parity ah okay um what would be useful in the corner seven would be more useful it would at least affect these digits oh bobbins I don't know um how do we think about this better so these are from one four six and eight these are from one four six and eight one four one fourth and eight oh so I'm sorry I'm sorry I'm just not I'm not understanding quite what I meant to look at here anything improved has this nine given me anything it's five this seven this two these are from one four six eight I feel um I feel it's this t-pen Domino that might do something that oh it could never be nine oh you can nearly do something in column nine look that that have to add up to odds so that's even overall now it's odd so these have to uh con uh conserve that parity so if that's seven that's got to be odd and if that's two that's got to be even just looking quite likely isn't it um whatever this is goes down here oh I'm sorry I I've hit an absolute brick wall [Music] um might be one thought I've just had is maybe I have to actually really think about the options for this cage which is a slightly terrifying thought is that really what I'm being asked to do could be let's let's put in the options there now if this was four six eight if all of these were even what would you then be saying 468 this would be one this would be one two seven so we'd have an uh what would we have there we'd have uh 18 23 yeah that doesn't work I think we do have to have one in here so it must there must be some parrot there's something parity-ish going on here just going on here I just can't see what it is that's odd if I don't include one in here those are even and then I either I can't include the two because that's going to give me 25 and that doesn't work and if I include the seven I get to an even total which doesn't work so I definitely need to have a 1 in there which means I definitely need to have a one in here this is not a one anymore and now if we think about the overall parity I'm going to be able to get this digit I think because I've got odd plus the one is odd so I'm uneven now plus two evens is even but the overall cage must be odd so I put seven in the corner how strange that is well that's useful for those two digits oh look now hang on can't I do that parody thing I was thinking about on this column as I thought these had to be the same let's just double check that that's odd that's odd that's even overall plus an even number five and seven or even so I need an odd number here to get to 45 which is odd there we go that's another digit um okay now is this useful well actually the one is useful now I've got a three nine pair up here so it's getting slightly better one idea I could do uh what have I got there 13 32 so I've got to split 32 between these such that both cages add to prime numbers that's probably worth thinking about but I just want to have a thing down here in a minute uh for a moment because I really would like to know I know I've got a one down here now and a four six or an eight how am I going to do all this disambiguation in the bottom of the grid oh I tell you one thing we might be able to do can we get these two digits it's possible that's probably what we have to do 13 okay well four and six would give us 23 that's fine isn't it um ah but 13 and 12 is 25. so we must have a six in here otherwise we've got a problem what about if we added 14 uh 27 is not prime so that doesn't work so we do it's four six aha right that's that is what we were we were being led towards one four six is what we have in blue so we don't have an eight so we do have an eight here which means we've got 2 8 here we've got 146 here ah no I want to do central pencil marking and we can get rid of get rid of the corner pencil marking here get put 2 7 8 here and no that doesn't hang on let's just check I don't think it's going to do much because I don't think we've got anything in the top parts of the grid that are going to be huge now okay all right so I'm going to revert to the other thought I had which was this column right so we're splitting 32 aren't we between these cages and the minimum value of this is five which would be Prime but it wouldn't leave okay that doesn't work um because obviously that would make this 27 which is not prime all right let's try seven uh 25 doesn't work either for this cage so that doesn't work three and six doesn't work because that's nine and that's not Prime on its own three and eight is prime that's 11. uh and eleven would leave 21 21 which is not prime so that's got to be a nine we've suddenly discovered um this is ludicrous right well 11 isn't going to work again isn't it because that's going to give me 21 again so we could take the two out of here if we have 13 we have oh we have 19 okay this is where it's gonna no but I can't have six that doesn't work because 15 is not prime 17 does that work with that 15 is not prime that's absurd that's so sad so this is 13 this is 19 and we know what those digits are which are two six and eight let's just double check so that that is 19. so 2 6 and 8 here oh hang on I've reused up and very many yes okay so I've used up rather a lot of even digits in this in this box already oh hang on I've just spotted some Sudoku I'm just going to do something no no bobbins that stop there being a three in the corner rotten thing wow okay hang on there's there's other Sudoku we can do as well don't forget your Sudoku in your Sudoku puzzles folks it doesn't help you five can go in that cage and nine is in this cage look at the bottom so Nine's in this one which means one's in this one uh four is in this one I'm jumping about all over the place I know there's some logic I can do up there but I suddenly saw the Sudoku um so we've got we've got five in there and we've got to add on another even digit well we could add on two couldn't we we could add on six and we could head on eight uh rotten thing okay um um all right okay well let's go back up here because the thing I was thinking about was that like what I can't do is put two odd digits in this Domino because if that's two odd digits they will add up to an even number and that's not going to be prime um because we can't make these add up to two so there must be a four in there which means that's a four that's six which means six is in one of those squares these these digits are all odd and this digit is odd obviously and this has got one odd number with it which could be one three it can't be five our case no that could still be five bother can it be no it can be seven oh it could be seven or nine wow wow okay that's disappointing wow um um this is weird isn't it so how on Earth am I meant to make progress from here I mean [Music] odd odd so we're we're on incorrect parity at the moment because we aren't even overall so these have got to be of different parities yeah that's it look at that that's so it's so good this logic is so good because now I can write in this digit so the puzzle is really clever it's fantastically clever because it keeps it's it keeps giving you something that it just doesn't seem to exist and yet it does so I could see that this had to be an odd number because I've used up my even numbers in in the box and therefore I could see I was going to get the parity of this and I was hopeful it would give me the perfect parody and it did because that is a one Cell cage that has to be even to make the row add up so just let me go through that again odd odd even so at the moment we're on even we've got to get overall onto odd but we know that's an odd number so that's got to be even to retain the parity and it's it's a one Cell cage so it can only be two this is no longer two there's now a five in this cage we know that this is odd I don't even think that's worth pencil marking is it all three of those are odd I I tell you what I'll do I will do that I will label them um I would normally do parity shading but I I've sort of not not gone down that route in this puzzle so I'll probably that's odd as well so we've only got one more odd in those digits hmm it's not going to be something like you know this no I think there must be loads of odd numbers that will work up here I was wondering whether they might I mean I can see one three and five for example won't work as the odd numbers there but I think there are lots of numbers that will try 159 doesn't work either one seven nine that will work yeah okay I think there are lots I'm not sure but I think that there are lots um thank you okay so can we do parity on this box now if we know that this is two we know that those six cells are overall even don't we odd odd even so we're on even which means these three cells have to add up to an odd number one of them is odd so the other two have the same parity so this is either two even numbers or or two odd numbers um I don't I think I can do that I'm not sure okay oh look I can rule out a two from the corner is that is this somehow going to be what we have to do next I doubt it now everything's been really pure to this point come on you have to think Simon you have to use your brain um okay what I will do then is I will think about row four because I can do some parity trickery here I've got a domino here that must contain an odd number and that odd number is a one because it can't be three five seven or nine so that means that this Domino which must also have one odd number in it has got a nine in it and the one here means that's not a one which means that there is a what uh look at this come on come on so now that I've got one and three in here by Sudoku and that's adding up to four and I'm going to have to add an odd number to that which is not five and not nine so this is one three seven I don't believe it this is beautiful isn't it oh no it doesn't fix hang on now there's a seven in here by Sudoku but it could have six with it okay um seven it can't have two in it actually there's no two in there and there's no 18 and there it is that is that this is done because there's seven in here and it needs an even number which is not four can't be two and it can't be eight because nine and fifteen are not prime so it is six so that's six that's seven that might help us maybe so six is now living up here which is not in the nine cage because nine and six is fifteen that doesn't add up to an uh another 15 is not prime so now oh okay so now we do have nine and six here which is which is odd we need to retain the parity so we need to add something like 2 to that or eight I think either might work 17 or 23. uh yeah okay so I can't do that this has got to be a five it's got to be odd and it can't be any other um number so that's five so these cells are now two four eight and nine I think to complete this box eight oh no I thought I was gonna get the eight nine nearly two it's actually it's we're whittling away we are whittling away at this um um although it's now it's oh that's not seven that's not six okay maybe a bit of Sudoku is what we'd have to do now let's try that I know nine is in here so I need to accompany that with maybe four or eight or two oh bother um over here what do we need we need to accompany this with two ah no eight can't go in here one and eight is not prime again so this is one and two and that means that this isn't two [Music] which means this is two which means by Sudoku this is two six nine and two six and nine do add up to 17 which is prime so over here we're left with eight and something eight and five and eight and five is thirteen which is prime beautiful um okay and now we know the contents of this cage as well which is one four and something uh not two not three not four not five not eight one four and eight which is 13 which is prime unsurprisingly so this those two digits are the same what does that do I must do something oh Bob bother bother bother two is it two in that no that's not seven I've just spotted a tiny bit of Sudoku so seven is in this one I think I can I am going to get rid of the O's actually let me get rid of the o um Corner mark I think I would just remember that this is this is two odd numbers added added on to a seven again it could be one three you can that would give us eleven very easily one nine yeah okay so we still don't know how this works five five can't go in this one oh five doesn't go there look maybe that's so we've got quite a lot of odd numbers down this column there's four in that that little congregation can all of those be even maybe don't see why not um okay botheration what am I meant to do to help I've uh three oh look it's Sudoku I've got a three five pair here now is that good has that cleared up something oh all right yeah okay where does seven go in this column that's very peculiar but it appears to only have one one place it can live which is there okay that's good so now these squares I see two comes out of this one oh this is a naked single this has become a six and I get a one four eight triple left so this square has to be the same as this one six comes out of these squares and I'm left with a two nine pair which doesn't appear to be resolved and I can't I can't now remember what I thought this digit was but we can get the parity of this one can't we odd odd so we're on the even at the moment we're still on even so that's odd which is one seven or nine I want to say which um good I don't think that probably is very good seven is a little bit restricted in in it's in one of those squares ah bother um can almost do magic look with these two in terms of parity I can see because because these three cells are odd obviously each of them is odd so at the moment this cage is on an odd total so this has to this Domino has has even parity which means it's either two evens which would have to be a four six pair that would make this a one or oh no that's it that's absolutely beautiful it's really simple it's really simple all you have to know is what do five different what do the five Sudoku odd numbers add up to they add up to 25 13579 so this although it is absolutely true to say these could by Sudoku be odd that cage would contain all the odd numbers and would add up to 25 and that's not prime so this has to contain two even numbers which have to be four and six isn't that beautiful and now that right so now this is nine [Music] um this is one that's going to give me a four here and a six here and that digit that's not nine anymore uh so we're on three five and seven for this digit now come on four six here there's a four in there apparently so four is in this top Domino up here could have seven with it um yeah so just to explain that obviously asking where four goes in row one is the simplest way to see that there has to be a four in this Domino oh we can probably narrow this down because that's that total is 18 at the moment oh 19 is prime so our seven doesn't work um because 25 isn't Prime and 27 is not prime so that I think this might have to be a one yeah that has to be a one it's the only prime number that works so that's well that gives me four eight eight four one okay that's now four one six come on please a bit oh no I thought I thought we were on the on a good track there I'm still hopeful actually I'm looking at how much we've done we've done quite a bit of this come on oh we're not going to get any threes in the corner though that three takes care of the last opportunity right um what on Earth am I meant to do now it could be uh we know that there's a four in here and we know that so is it something to do with other odd digits then this has got to have two odd no we've got one three five now the nine could go up here could it nine and four is okay seven and four is okay right okay let me think again do I know I must know that I do know the parity of this digit I just keep not writing it in um all right let's try what could we do what could we do instead two by Sudoku is in one of those two cells I don't think that's going to be that's not going to be the clever thing we need to do is it uh wow oh look one there we go I've got more more Sudoku I can do in this column maybe that's going to help me so six now one of these squares but you can't oh we can't put six in this Domino because there's a four in this Domino so six is now in those squares and look at that okay so now we can ask where six goes in row one and it's not in any of those cells which means that is in the corner which means now I get a 2 8 pair here oh I thought I was about to break the puzzle because I could see that was putting two in one of those but two is fine um okay oh I don't know I think uh what do I think let's let's these squares here are from four seven and eight no not yeah that's right isn't it not four seven eight seven eight and nine I should say seven eight and nine and I know there's a seven up here I can't put an even number in that top box so this oh no hang on no it's there's a four in the corner sorry sorry I just didn't see it I went up to all the trouble of noting that the fours were placing a four in the top row and then didn't see that there was two fours looking at this we get a four in the corner that's seven or nine both of which work um two four so that there are six and eight in this cage then I suppose is that gonna be is that correct I think it is so six and eight is fourteen two oh we can't add seven to that so we must add nine to it and get 23. beautiful so this is a seven in the top position which means this is not seven this is six eight nine I don't believe it well that means that's not seven I suppose that's not seven maybe that's important three five yeah that gets me a seven here and a one three pair oh I know one thing we could think about now we could think about how to make this Prime couldn't we because we know that this is odd let's actually put in all the options and we know that by the secret uh we've got 45 for the row minus 19 so that's 26. so the sum of these cells is 26. well I can't make this one then because that's going to add up to 25. um three would work wouldn't it I think three would give us 23. 21 doesn't work so we can take five out so this is this is this is being oh I've got a three nine pair now can I get rid of nine let me just think about that no uh no nine nine will give 17 here won't it and that will work I think bobbins bobin smoke bobbin's face I think that's what we have to say okay but eight in the top row is now definitely in that cell and there has to look at that now there has to be an even digit in this Domino or it cannot add up to an odd number so the two goes there which that is doing work what a remarkable puzzle this is still going okay so now this is odd for sure and it's not one but it could be three it could be five can't be seven that would give us nine here and it cut it could be nine as well so that's three five or nine all of which seem to be possible and I saw this three nine pair here and okay and we know that there's a seven up here as well I I just don't think this is going to be restricted enough although okay so I can't have the other of three or nine in the cage can I so it's going to be three or nine seven and one or five and that's it you can't put five that's as simple as that you can't put five in the cage ah it's so clever but you can't because if you put five in this cage five joins up with seven and makes twelve and whether we add three or nine to twelve we're going to get 15 or 21 which are not prime so 5 which can't go with the four of course I think that's been available for ages that's a five that's a three that's a five okay has that done it this is no longer a three this is now exactly equal to nine so that's nine that's three so we've now got 16 here uh and the other digits got to be a one so to make 17 so 1 and 7 go in this has got to be a three four pair which means we've got the one two the two the eight the eight the five okay and hopefully we'll be able to un unscramble the top of the grid maybe uh we need this Square to be one no one or nine only can't be three because of this one what's this digit that's that's got to be a one okay well that's going to make this a nine which is going to make that nine that three that three that one let's double check this adds up to a prime number we've got 14 17 that does that's a five that makes this seven which is fine five three three four four six nine here eight here six here nine two two eight one seven and seven there but a brilliant puzzle that is nil oh my timer didn't start why does it do that sometimes I don't know 100 people have sold that in seven days well there are a hundred very happy people I'm guessing that was fantastic absolutely fantastic it's basically a parity exercise combined with some remarkable choices of sort of numerical division so whatever it was in that 32 thing that we had to divide in that column between two cages and there was only one way it worked things like that were going on I think I think there were two or three bits where I could have got the logic more quickly I think there's something going on with this green cages I couldn't see I couldn't see that smoothly enough and I think I I think I have a feeling that this being a five was available more earlier not sure though it's just a sense I got as I was feeling through the solve but I loved that that was brilliant let me know in the comments how you got on I enjoy the comments especially when they're kind and thank you to agent for a Stella Stellar puzzle and we'll be back later with another edition of cracking the cryptic laughs [Music] [Music] [Music] [Music]

Channel: Cracking The Cryptic

Views: 45,206

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Id: GrxpRaOBDHo

Length: 60min 27sec (3627 seconds)

Published: Fri Jul 28 2023