math shortcuts plz?

[AC1D]

Hey, i saw the vedic math thing and thats kinda cool. Can u all show me some other shortcuts or tips in math? Websites with them work also.

[alkatran]

I speed up all my math by remembering certain things (KNOW YOUR MULTIPLICATION ABLES )
For example, 9+3 is the same thing as (9+1)+(3-1) or 10+2
or.. 9*8 = (10*8)-8
8*8 = (5*8) + (3*8)

x^2 - a^2 = (x-a)(x+a)
^A simple quadratic equation, but it helps.

5*5-1 = 24, 4*6 = 24
5*5-4 = 21, 7*3 = 21

For division, if I had 100/7, I would do the highest multiple of 7 in a 100
70+28 = 98 (7+4 = 11)

then divide the rest and add it on
2/7 = 2/6 - a bit
.3*7 = .21 (too high, but close enough for me)
100/7=~11.3

I learned recently that Sqr(8) = Sqr(4)*Sqr(2)
which means that Sqr(8) = 2*Sqr(2) (which is approx 1.41)
Sqr(8)=~2.82
*sqr = SQuare Root

Simplifying them down to what you can do in your head...
45*32 = 40*32 + 5*32 = 40*30 + 40*2 + 5*30 + 5*2
45*32 = 1200 + 80 + 150 + 10 = 1280 + 150 + 10 = 1440


These are the tricks you teach yourself in elementary school, but never really notice it. The fact that I paid attention gives me a huge advantage other people who didn't.