How to Calculate Faster than a Calculator - 5 (Mental division) by mathOgenius

let me ask you a question try to do this problem mentally if i were at your place i wouldn't even try because problem like these exceed the short-term memory limit of human mind so we humans simply cannot do these problems mentally or can we so in this book i learned a really cool trick known as gastimation with which we can solve problem like these in a very little amount of time with insane precision our answer wouldn't be accurate but it would be really close to the real answer making you a super human calculator so with this let's begin so hello geniuses welcome to the fifth part of method genius mental man series and also a very big thank you for helping me to reach out 40 000 subscribers which is insane and also after i started to host this channel the subscribers are increasing at accelerated rate so thank you so much for that and also thank you for your love in this mental math series also so in this mental math series we have learned addition subtraction multiplication a lot of cool mental matrix how to memorize numbers now it's time to learn division now for multiplication other stuff i had to teach you the left to right method which was new for you but see how do we do division on paper yes we go from left to right so there is nothing new to learn in mental division the same rules apply in here too as you do it in paper from the school times okay so there is no learning left to right method in division so i do not need to teach you that so what i will teach you in this video is a way to do that even faster like estimation and learning fractions so the first of these is gusty measure now gastimation is a really cool trick which takes your creativity now the more creative you are the better you will be at it in this guesstimation we hunt for nines ones twos etc we basically need to round up or round down the numbers to make a simpler division problem so let's learn how to do this problem with gastimation in just five seconds now take a look at this horrifying number now we need to convert this horrifying number into a simpler number we can do this in two different ways first we can round down that one but it would still look horrifying so we will round up that nine which will make it nine three zero zero zero zero zero now this is a simpler number now take a look at this number now you think how to simplify this one so in this one we can round down that 2 to convert it to 18600 now you will say why not round up 8 now because in gastimation we play at the line we need to convert the numbers into simpler numbers but not change their nature this is where it takes creativity now we have this now these three zeros cancel and we have 93 000 divided by 186 so as we do in paper 930 divided by 186 now in here you can be a lot faster see 930 is a lot like 1000 and 186 is a lot like 200 so two fives is 10 right so let's try multiplying 186 with five and now for this specific problem 186 fives is see 500 plus 400 plus 30 which is simply 930 so 186 fives is 930 and 500 is the answer so our answer is 500 we should not be proud at it right because we have changed the original question a lot and our answer should be very very wrong but you would be amazed to know that the real answer is 499.02 so our answer is really close to the real answer which is insane and these two numbers are not special numbers made by me this one is basically the distance from earth to sun in miles and this one is the speed of light in miles so basically light takes 500 seconds to reach from sun to earth this is we have learned in school right so we normally say 500 not 499 so our answer is really really accurate this is because you rounded up the first number and rounded down the second number this decreased our error so this is basically all the guesstimation you need to know now you don't realize yet but you can use this cache dimension to a lot of problems because in a lot of problems there are nines and ones which you can manipulate and also this is really helpful for science students in which there are a lot of big numbers you needed to divide but you don't have access to calculators in exams there you can use this estimation to get approximate answers and good mark so basically roundup round down with some creativity is gastimation now it depends on you how much you practice now for practicing i have specially made a game known as math globe run in this game there is a good blob and there is a bad blob and the bad blob is chasing our good blob and who wants to eat it but solving mental math questions will save your blob and trying to get the highest score in the leaderboard is really cool too so downlink of this game is in the description of this video now the second thing that i will teach you is fractions now learning fractions for division is really important like you need to know what is one by two which is point five you need to know what is one by three which is point three three three and so on like this so i will teach you some really cool one which will make you look like you are insane superhuman calculator so first basic thing is this see if you know what is 1 by 4 which is 0.25 then you also know what is 3 by 4 because 0.25 multiplied by 3 is 25 375 which is 0.75 so this is you need to remember like sometimes people like start dividing three by four which is not efficient way to do it you know one by four multiplied by three okay now a really cool one see what is one upon nine simply zero point one one one one one one and so on what is two by nine point two two two two two and so on what is three by nine point three three three three and so on till eight so eight by nine is point eight eight eight eight eight eight and so on so this is really cool while dividing by nine for example in a problem you have a remainder eight now do nothing that your answer whatever it is point eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight eight edited and so on this will make you look like you are a superhuman calculator now another really cool one is what is 1 by 11 it is 0.09090909 and so on now you know what is 1 by 11 so what is 2 by 11 so 0 9 that is 9 multiplied by 2 is 18 which is 0.18181818 and so on now from this 1 by 11 try to find other two for example what is 5 by eleven so nine fives are 45 so point four five four five four five four five and so on so while dividing by eleven whenever you have some remainder you can use this now the last but not the least the fractions of seven these are really cool now for this you need to remember a small string of number okay but it's worth it it will really make you look like you are some god of calculation something like that so the string of number is this one four two eight five seven say it again again one four two eight five seven one four two eight five seven now if you have remember this you have done a really cool thing so see one upon seven is one four two eight five seven one four two eight five seven one four two eight five seven and so on like this repeat now look for a pattern in here two upon seven is two eight five seven one four and two eight five seven one four two eight five seven one four this pattern is repeated in all the fractions of seven like this now how to know from where to start this sequence now it's really simple so let's understand this by two by seven so we know what is one by seven point one four and so on so multiply 14 with two we get 28 so two is basically the starting of our sequence so wherever two is in the sequence which we have remembered start from there for example in here we have two so two eight five seven one four now we have one four one four two eight five seven one four two eight five seven one four two eight five seven now this is really really amazing because with this whenever you are dividing with 7 if you get any remainder then you can show off this trick so let's demonstrate it 45 divided by 7 so 7 6 of 42 a remainder of 3 this is simple basic now we have a three by seven now let's use this trick in here so in here three by seven multiply three with fourteen so fourteen threes are 42 so four is over that starting number so what is the sequence that you have remembered point one four two eight five seven in here four so four two eight five seven one four two eight five seven now you can say this like this six point four two eight five seven one four two eight five seven one four two eight five seven and so on now everybody will think that you are calculating but you are using this trick and this will make you simply a super human gold like calculator this is really faster than calculator so yeah this is a really cool trick also while performing this one you can also like act like you are calculating but you are not you are just saying a string of numbers that you have already remembered so this is sometimes those mental mathematicians use to impress their audience now do not only limit yourself to these fractions learn all the fractions they are not tricks for them but you should learn them so these are all the basic tricks which i learned in this book for fast mental division also in the series we have learned addition subtraction multiplication division and also memorizing numbers so basically we have completed our basic mental math series now for now this is the end of this series but as soon as i learn something new in mental maths like those finger math etc etc i will add more videos in this series so for now this is the end of this mental math series so thank you for watching this mental math series and always remember that math is everything

Channel: mathOgenius

Views: 256,142

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Id: 4ZhWXvXxF7A

Length: 11min 7sec (667 seconds)

Published: Sat Feb 13 2021