How to Do Math In Your Head : More Fast Multiplication Techniques

[SwissMexProductions]

Thanks man very usefull. Seems like we forget these things very easily

[machineryProducts]

thanks dude i have a test tomorro and you really helped me thanks

[KnowledgeIsPowerKiP]

When I do these I just break them up into easier multiplications,

For example

91x94 = 91x90 + 91x4=8190+364=8554

[xXShonomercyXx]

Calculators are wonderful!

[OhWowLovelyXx0]

Ohkay. But what if the number is passed 100 like what if it's 355 do you round that to 400 or 300?!

[KnowledgeIsPowerKiP]

@OhWowLovelyXx0 Even if the number is really big you can just break it up

lets do 387x513.

=387x500 +387x13=500x300 +500x87+387x13=150000+43500+30­0x13+87x13

=150000+43500+3900+87x10+87x3=­197400+870+261=197400+1131=198­531

and no i did not use a calculator

[robertbutler714]

is there anything expert village doesnt have videos about?

[koldblooded1]

expert village is finally coming through on somehting haha!! well i seen some of the others not htis one yet

[KocirovD]

it so complicated !



[deadfuk69]

you don't need to do this crap for multiplications just know your times tables by hard and you don't need to bust your head over nothing. You can maybe use that technique for the big problems.....but it's complicated..

[princejackie]

Mike Byster is better :)

[TomKaren1994]

94 x 91

90x90 + 90(4+1) + 4x1 =

8100 + 450 + 4 =

8554.

Just multiply left to right. That's the way I've always done it.

His technique is based on the trick to find the hundreds place quickly.

(100 - A)(100 - B) =

(100)(100) - 100(A+B) + AB

(100)(100 - (A+B)) + AB

To find (100 - (A+B)), just take one number, already either A or B less than 100, and subtract the difference of the other number and 100. Put that value in the hundreds place. It's no trick. It's math.

[loveseriousful]

what if its over 100 ? hmmm ?

[nice4ever100]

@loveseriousful MAYBE INSTEAD OF HOW MANY LESS THAN A 100 IT WILL BE BY HOW MANY IT PASES 100 LIKE IF IT IS 104 IT WILL BE 4

[mathmatchpoint]

If you want to become good at Mathematics go to my channel: ( Mathmatchpoint ). In my videos I'm going to teach you Math the easy way. I'll teach you all Math topics; from the basic to the advanced topics. I promise that you will become good at Math if you watch my videos and do the provided exercises. You can watch my Math videos in order by clicking on Playlists.

Math is easy if you have a good teacher

[indigo325]

kutte kamine...jitna gyam tum din bhar mia sekhte ho utna to hun 1 min mai toilet kar ate hian......samjha america

[arow333]

I noticed that you could use this method for numbers greater than 100, like 217 x 189, if you first do it with 21.7 x 18.9 and then multiply by 100 at the end, but at that point it is no longer practical. It seems that doing 217 x 189 the conventional way would yield the wrong answer (assuming my math is right).

[10072018]

Holy god that's complicated.

[alchemist940]

Has there ever been a useful expertvillage video? :/ This is more hassle than just about every other method out there.

[93curt93]

dude u rock!!!!!! NAT

[VendectaSplitter]

Tua mamma!

[youlovemathematics]

Youlovemathematics. On my channel I will teach you everything about math step by step. I will start with teaching you (necessary basic math skills) and then I will teach you the more advanced math topics. Just click on Playlists when you are on my channel and you will be able to watch my math videos in order. I promise that i will teach everything in an easy way. Math is easy if you have a good teacher.

[gandolflitke]

Good method, But Im not too good with numbers. So when you have lets say 97X125 for example I have a real hard time with it. But I can do lower basic numbers almost instantly. And when figuring higher multiplication problems it helps to be able to figure lets say 7x9 etc. to know that part of the whole problem.

[9308323]

@gandolflitke You can do it like this:

97=100-3

125=100+25

125-3 or 97+25 =122

25*-3= -75 (positive x negative = negative)

So, 2200 (added two zeros) -75 would give us 2125.it's easier since we are multiplying something by 5's

[getrengcle]

Ineffective! Too slow.

[9308323]

@getrengcle The methods seems very slow when you're explaining it because it's made for everyone to understand but it's very effective when used hands-on. Definitely much quicker than usual method. Try practicing this when you have free time and just like he said, It'll be much quicker with practice :)

[HDVLAD]

The Russians made this up.

[STUFFRANDOM123]

@HDVLAD in russia we make you up

[MegaDotaallstars]

nice like it

[The2Blox]

he teaches it much harder

[ladypena]

I dont get it :'(

[SuperAsher10]

this is so cool how do you come up with these cool math tricks its like in any video some cool math trick!

[CrazyaznXD]

This method does not complely work!

like 10x10 with the method

sometime u can;t mentally do it in ur head

but most of the time it work :D

[endlessmountain]

If we take a number like 27x55 we get (73 - 45) as the numbers to get 100 using this method

The subtraction gives us -18 and multiplying 73/45 is 3285

This is interesting because -18+32=14 and the answer is 1485

[abdikadkir]

fack you

[endlessmountain]

your a cheery person. You have as much love here as Hitler did for the Jews. Heck maybe you maybe his re-incarnation and its supposed to be this way.

Thank you for the message mr Nazi

[poopball3]

he'd already said that: this method doesn't work too well when you realize the result number is larger.

[Don0chi0cho]

theres this exam that you must do in your head for 5 mins 20 question...they give you like...ex: 345+531 or 23x63.. all multiply and plus only in 5 mins.. in your head no scratches on the side of the paper.. this method cant help..its actually a dealers exam in a casino...any one can point me a video where to go for does example i just gave?

[WePrank4Fun]

look up and learn the abacus it is by far the easisest way to actually calculate these numbers. i heard that in a year or so u can actually be able to visualise it in your head so even more helpful

[LivOlivia1]

that method doesnt work well unless the numbers youre multiplying are actually in the 90s

[wingler000]

@LivOlivia1 if it was 46X49 then the base number is 50

[9308323]

@LivOlivia1 It does work with other numbers like 76*84=6384. However, it isn't as convenient as other methods since you have to know that 24*16=384 or else you'll get a wrong answer or it'll take you quite a time just to find out the answer.This method is very quick even the first time I tried it and I was very impressed with the accuracy over time you spent to get the answer.Various methods have their own pros and cons so switching one method to another without having to start over is must have

[osnai12345]

hah! tell me how are you going to get the answer in 87x75 when after performing that technique which gives you 62 you have to do it again to have your second answer because it gives you 13x25 then you'll be back at 87x75!!!!

[interestingramble]

you just make one. I'm stupid, and I can come up with one for almost any relating group of numbers.

[interestingramble]

I have one too for 90. For the first two digits you times 9_X9_ then add the latter two digits, and it will always be the third number. Example 93X93 = 86_._ The product of the forth digit = 3X3 or 9. For the third, it's the sum of the last two digits - 10, but you have to be careful bc sometimes the product is over ten (of the other two), and you have to add ten. it's a good way to chech your answer. I've been doing the first two digits w/o realizing it awhile.

[nickolayer]

Besides, "more fast multiplication techniques"... what would you say of the word "faster"?

[7cujo7]

threy had another clip called "fast multiplication techniques" So now they are giving you more of them.

[nickolayer]

Ah, I'm sorry - that's my mistake, then.

Doesn't sound that good to me anyway, though... "more multiplication techniques" wouldn't be confusing, I suppose.

[BalthazzarCH]

0:12 ... he already made an other video, these are "more" fast multiplication techniques .. not "faster" ones than the others.

[nickolayer]

Thanks for pointing it out - I know, I was kinda careless when I wrote that :-(

[soopertrooper001]

lol, what ever happened to cross multiplication?

[ballocoke]

that's not fast at all!i can do the "conventional"way much quicker.

[Willawaard]

Ahhh! You can apply this method with a different reference number. He uses "100", but you could use 20, 50, 100, 200, 500, 1000, etc. It's neat but not completely useful.

[snarfalopogus]

its useful if you dont have a calculator on you :P

[TriwaveTM]

Your system only works for numbers between 90 and 99, for 80 to 89 you only keep the first digit of the subtraction, and below that your system completely falls apart - for the amount of times I have ever needed to multiply any such numbers in my entire 39yrs on earth isn't worth the effort required to learn this - and I'm an electronics engineer, I use maths every day. The easiest method I know of is to multiply up in 10's and units adding as you go, far easier and more accurate.

[Humancyclone7]

thank you for acknowledging the difficulties of a low number but is there any remedy???

Also what if the number(s) were over 100??? plz reply and great vid!

[awesomemarts]

you need to carry the 3 across ....62 & 345 add the 2 & 3 together 6545

[Chell4]

I never got that. Does the answer always have four digits?

[kjaan]

This is vedic math. You can get a better explanation of this method from youtube by search vedic math(indian).

[nickolayer]

Vedic math?? What on earth do you mean?

That's basic knowledge everyone must obtain.

If counting 72*11 is magic, then 72*10+72 is probably not! I like the idea of calling this "vedic", but that's something everyone can master, and usually without memorizing all these tricks.

[chaoz87]

77x85?

I tryed it and it didn't work.

[shortie0306]

you probalbly did it wrong

[PSpeopleYouRtube]

how to do 24 x 40

[Nickyd614]

distribute the 40 24*4=96 or you could think of it as 12*8. after that just add a 0. and the answer is 960

[codecaine]

960 just add a zero at the end and multiple the rest by 4

[PSpeopleYouRtube]

thanx again

[andirlyn]

tanks

[ryann5432]

if it is 90+... many operations may be used so it will be a waste of time... this vid helped me just a little!!

[ryann5432]

i mean if it is below 90!

[kkandozha]

boobs

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(.Y.)

[LePombaer]

may help in some rare situation, but if it isnt 90+ its useless

[isantoso81]

so how do you do 26 x 37 ?

[PSpeopleYouRtube]

26 x 37

74  100 take away 37

[codecaine]

thats a long way to of doing it. There is a shorter way

[pickerjones]

through using this method...i have found out that with some equations for example 99x92 you get 918 instead of the correct answer: 9108. so in some cases u must add a 0 if u are working off the base of 100 and 00 if u are working off the base of 1000 and so on

[Daimons2332]

The explanation sucks!

Actually you have to add 2 more numbers to 99-8.

So, the answer is 9 1 _ _, to get other 2 numbers multiply 1 with 8 and get 08, so the correct one is 9108. It is nothing to do with zeros, just add 2 digits in case the base is 100 and 3 digits if the base is 1000

[360gamer4life12]

@pickerjones no shit sherlock

[gandolflitke]

@pickerjones Your missing a step, you use 100 as a reference #. So when you subtract 1 from 92 or 8 from 99 you get 91, you then times that by 100 which would give you 9,100. You then times the 8X1 and add it which would give you 9,108. the same rules apply with lower numbers, and above 100. hope that helped.

[pimpmyride666]

That's good but it doesn't work on all 2 by 2 multiplication. To solve any 2 by 2 multiplication problem, for example, in 73x54, multiply 73 by 50, remember that number while figuring out 73x4, then add them together.

[oxy00moron]

yes..the most important thing is to be able to visualize numbers in our minds..

[sustaesiste]

Brilliant!

[boredashell333]

thanx man this helped a lot :)