Math Hack

[---kqcv]

For everyone saying ‘‘Omg I put it in a calculator and it is correct’’: stop. the method only works when the last 2 digits are 1’s. Simple algebra can prove this.

I will use n and m for the 2 2-digit numbers that are being multiplied.
n and m can be written as 10a+b and 10c+d, where n = 10a+b and m = 10c+d.
a is the first digit of n, b is the second digit of n, c is the first digit of m and d is the second digit of m.
because we gave n and m a second definition, nm can be written as 100ac + 10ad + 10cb + bd.
This because of the identity (a+b)(c+d) = ac+ad+bc+bd

In the video they claim nm to be the following:
bd + 100ac + 10a + 10c

This is what happens if we equate the 2 expansions:
100ac + bd + 10(a+c) = 100ac + bd + 10(ad+cb)

This can be simplified into
a+c = ad+cb, which is only true if both b and d are equal to 1

Because b and d are the last digits of n and m, I’ve just proven my statement

[slimegood]

People who passed 4th grade and know how to do cross multiplication:

[LuzonBall]

Man's breaking all the rules of math💀💀

[ilyvjj]

my teacher if i tried that : "howd u do it? show ur work."

[Willow.on.paws]

Me using a calculator to make sure it's the right answer

[Clever]

٤٥
×
١٣
٥٨٥

٥*٣=٥وفوق الأربعة ١
٤*١+١=٥
٥+٣=٨

[ShortArtGuy]

Me who is normal: “no u did da math wrong 🗿”

[vlogswfayoriginal]

If I hear this song one more time I'll blow up into smithereens

[JayMack]

people be like:

YOU MADE ME GET AN F ON MY TEST

[Blud_buddy_theUhhIdk]

Bro Endorsing Calculator And Now Everyone Open Calculator💀

[TootieBlasters]

2nd grader: “is this the power of a god 👁 👁
👄

[michaela]

Me checking in calculator to make sure it's right 👁👄👁

[Baller_LikesBorgir]

10 yo Asian me already learning the Diophantine equation: 👁️👄👁️

[donovanmacatee]

Calculator: I’m about to end this man’s whole career 😅

[Peachy_Queeny]

POV: Me calculating it me seeing the results 😮

[claweerblx]

1x1 is 1 drop it down below 3x1 is 3 drop down the 31 drop down a 0, 4x1 is 4 you got 04 4x3 is 12 you got 1, 240 add, 1, 240 plus 31 is 1, 271 I learned this years ago

[seemarana]

Being an Indian i calculated as soon as I saw it 👁️👄👁️

[heatnice]

me who loves math this really helps sometimes

[alyssarees]

Me in yr 4: ur too late I've already finished that-

[Simply_Rebeccaa]

This is more confusing then the normal way