Sudoku Tutorial #40 A must know technique. NOT a puzzle.

[Music] [Applause] hello everyone here we are again Robin this cool guy with another tutorial this is number 40 before I show you what I have to share today let me talk about a couple of things first of all I've had people say to me why do you bother to put in little numbers I can do difficult puzzles without having to put them in well there's two things I'd like to say about that first of all if you can put the do you if you can solve a puzzle without putting any of the small numbers in you're either very clever or you have a puzzle which says it's difficult but it's really not now if you remember rightly back in lesson number four I mentioned that if you're doing really easy to medium puzzles all you need to have in each cell is two small numbers but when you get to the stage where you have a really difficult puzzle you've tried everything you can think of duty and BLC are across me technique 3x3 all those advanced techniques and you're still stuck now what do you do well I'm going to show you because this is tutorial and the next one are based on what I would call advanced outside the puzzle let's have a look at this okay in this particular situation let's say just for an argument to sink that you've got to the stage where wow what do I do next well this is the time you could probably go to use the outside the puzzle system or technique as I called now if you look at this puzzle you'll notice that there are places where there's five or six empty cells in a row column or block and my suggestion would be this always look for say something that's only got three empty cells in a row column or block work those out first then go to any row column or block that's got four empty cells and so on until you got five empty cells and on this particular tutorial I want to demonstrate what you can do with five empty cells what I'm going to do now is show you what you can do with as just as an example to show you in this case it's going to be a row with five empty cells and it's going to be this one here step one we look along this row and see work out what numbers are missing well there's a one there's not a two so we put the two over here outside of the puzzle three there's not a three along here we put that over there four there's a four already five there's no five along this row so we can put the five in six is there already seven there's no seven either of what is seven in eight is there an eight along here no there's not nine yes we have one so we have five empty cells and the numbers that can go in those five empty cells that could be a two or three or a five or seven or an eight now that's step one now comes the part where a lot of people will say I don't want to be bothered doing this because I've got a computer that will put all the possible numbers in for me well if you want to go that route that's one that's okay but the purest Sudoku solver will say well part of the skill of solving Sudoku is knowing what numbers doing each what possible numbers go in each of these cells and that requires a little bit of brain work it's up to you of course but I'm going to show you if you don't have a computer if you have a book or something like that and I use books a lot so when I start with this cell and we'll work our way across I say to myself okay is there one yes there is a one there's the one that one this so you kind of a 1 there is there a - ok - have a look here is there a - well here's a 2 so you can't have a 2 there because you can't repeat a number in a row column or block and so we can't have a - what about it a 3 is there a 3 in this block is there a 3 down here no there isn't is there 3 no I don't see a 3 so 3 is a possibility for we've got a 4 5 we've got to find 6 we've got a 6 if you've got us 5 and a 6 the four in that row means you can't have a for there 5 and this block meet you can't have a fire there or a 6 ok let's work the but the next seven well is there a 7 in this block is there a 7 along here no is there a 7 down here no there isn't so we can put a possibility of a 7 here 8 well there's no 8 in here but there is an H down in here so you can't have an 8 so what we're saying now is the possibility of any kind of an on by the way you in this so only 2 possible numbers can go there how many of those - let's do this one now yeah we already have a 1 do we have it - no we don't mean you put it to me do we have a 3 there's another 3 in here there's no the 3 along there there's no no three down here yes there is there's a three right there so we can't have a 3/4 is spoken for five is a five in here in this block there's a six in this block you can not an accountant what about a seven yes we could have a seven and what about an eight is there an eight in here no is there an 8 down in here no we could have an 8 there 9 we've already got a 9 so now we've got two cells now what about one here well we have a one in this block so we can't have a one there we have a two in this block because we can't have it - what about a three is there a three down in here no there's not a three in there there's not a three in the block so we can put if possible three four we've already got a four five well if I look down and there's no five in here and if I look down in here this column there's no five so the possibility of a five is there as well six we've already got a six seven we've already got a seven in this column 8 and 9 we both having this same column so we have a possibility of a 3 and a 5 year now let's go over to this one what about um what are we missing we're missing a 1 when we gotta want we don't have a - I don't see you two in here so we put it to me what about a three we don't have a three down in here so there's going to be a three what about a four we've got a four five is there a five down in this column we know there's not a fight along here there's not a five in here so yeah could be a five six when we've already got a six seven we've already got seven eight we've already got an eight in this block and we could have a nine is that right well okay we could have a nine we can't have a nine is an on along here so miss that nearly so that is a two three and a five now let's go to this last one we don't have a two we don't have a three we had a one we kind of away in yet over one year two three three four four well we've got a four we don't have a five coming up and down in here so it has to be a five as well and six we've got a six and seven we've got a seven in this block eight we've got an eaten block eight nine we've got a nine across here so 235 are the ones that going now in that particular those cells now what we've done here is that we've we've worked out what possible numbers will be there now how do we know which ones well here's the step that we go through first thing is you look along the row of little numbers and is there a number that hasn't been repeated in other words it's only there once have a look closely and did you notice this it's an 8 in this row and all those little numbers there's only one place an 8 could go which means you be it means that you can get rid of all these little numbers here and put a big 8 in there we go let's do that make it nice and neat and clean so we're gonna put an 8 in there so let's do that so we're on the way now we come to the next step and you may say well what do you do now well I could have an 8 there under there but did what is that going to get me well it won't get you there look we on an 8 there we've got an 8 there we've got an 8 there so if that's the case if this is the case here we know we have to have an 8 down in here there there or there we can't ever there because of that right we can't have it there because of that way so this will become alright we will be we've got something as a result of finding that lady doesn't always happen that way but what's that you're now stuck just as an example you're stuck and you say what do I do now well here's the next recommendation go ahead and solve the puzzle the best as you can and let's say you come across a new number that helps you let me show you as an example let's just say for argument's sake just so you understand what I mean that a 5 turns up here one of the ramifications of that here we have a left your ever right in this block it has to be in the center now we cannot be there because it's a 5 there which means that this has to be the 5 so let's erase the 3 and the 5 and put in a big fight Wow can you know what's blue today put in a big five so we've got a 5 now what's the ramification of that 5 that means that any other 5 along this row you can get rid of so we can get now now we can get rid of this 2 this 5 and this 5 and just for fun sometimes you can do this we've got rid of the five we've got rid of the eight and so on now when you've got this two three two three you have of course a matching pair and we know from previous tutorials and lessons that if you have a matching pair any other two or three in this row can be eliminated which means that this three can go and you finish up with a big 7 okay there's your big 7 now we know from that video 7 could be there and there but let's move on because we now have a 2 3 2 it's 3 left we've only got 2 little numbers left and we know that if you get one you're going to get the other one so we can get rid of the 7 now so you're left with 2 or 3 now just say for argument's sake that as you work on the puzzle you come up with a 3 here just to demonstrate what I mean now you have a top we have a middle over here we have to have a bottom and that's the only place it can go so that becomes a 3 now what's the ramification of that well that means that this freaking go and you're left with a big 2 so we put that big 2 in and it like most matching pairs once you've got the two there we can get rid of that too and it becomes your three now what isn't this incredible what we've done is that we have now solved that whole row based on outside the puzzle system now next tutorial I'm gonna do another one of these but to show you how it can change again [Music]

Channel: Sudoku Guy

Views: 1,158,461

Keywords: Sudoku lessons, sudoku tutorials, sudoku techniques, sudoku tricks, sudoku hints, sudoku for seniors, sudoku for the frustrated, sudoku for the family, sudoku for beginners, sudoku for advanced, sudoku for dummies, how to solve sudoku puzzles, how solve sudoku, brain fittness game, Sudoku, Learn sudoku, Learn sudoku step by step, Brain fitness, Demonstrations for sudoku procedures., sudoku procedures.

Id: ld0hChtBLno

Length: 13min 41sec (821 seconds)

Published: Thu Jul 26 2018