math is so easy

can you mentally calculate

Category:

Education

Tags:

• math
• mentally
• calculate

[frankman55]

Sounds like my old kindergarten teacher. "What comes after 3, in counting? 4. isnt it."

xD

[idolkritiq]

conditions conditions conditions ... MAGIC = Calculator!

[Memorandum1231]

ahh wonderful..

[RamdomVideo129]

OMG OMG OMGO GMOGMGOGMALAALALALALALALALALAL­AL

Thank You So Much :D I Was Having Like SOOO Much Trouble

in School with Math. Now this Epic Guy Showed me a super Epic

Way THANK YOU SOOOOOOOOOOO MUCH!!!

[seanpaul320aaa]

go to Brasil ll make a lot of money there once they dont Speaking ENglish they can copy you

[seanpaul320aaa]

very nice  Great super easyer cool.!!!!! rsrsrsr

[AviarPlus]

@taolahuy1681993 No it doesn't work. it works for 72*78 cuz 2+8=10 but in the case 75*72 there is 5+2=7 and it doesn't work. This is Berulius multiplication rule.

[taolahuy1681993]

How to do 75* 72, 82*82, 91*92 in this way ???? It doenst work

[nwoooooooful]

wow, so practical!!

[ex59neo53]

his first example can be calculated mentally in less than 2 secs if u know that 2x2=4 and 3*4=12.

33*37=35²-2²=1225-4=1221

[ex59neo53]

if u know 2 things :

x²-y²=(x+y)*(x-y)

the square of a number finishing with 5 is : (10x+5)² =100x²+100x+25 =100x(x+1)+25 so will be read like x(x+1) followed by 25

example : 71*79=(75-4)(75+4)=75²-4²=5625­-16=5609 (7*8=56)

In fact in those "maths" u only have to know your square numbers calculus