Silly Math Tricks

[do it easy]

More Math Tricks

Confuscious said:

"He who can use math tricks is probably good enough with math that he doesn't need the tricks."

2.5 x 30 = ? (The answer is not obvious)

Change it to:

25 x 3 = ? (The answer becomes obvious)

I would have broken it down differently, using Rainer's prime numbers

2.5 x 30 = [5^2 / (2x5)] x 2x3x5

after re-arranging the terms

= 3 x 5^2, which is obviously the prime factorization of 75 ta da!!! :banana:

Alternatively, you could use Limey's multiply/divide by 4 technique!

2.5x4 x 30/4= 10 x 7.5 = 75 same answer!!!

I learned it all on the internet!

 

[jjones9527]

I would have done 2x30, then .5X30, add them together = 75.

 

[Kevrumbo]

Catherines's thread of almost a year ago has a whole bunch of neat math tricks (and histrionics too!). . .

 

[FLDVR]

That thread by Catherine is quite interesting. Thanks for pointing it out.
Henry

 

[Cave Diver]

That thread by Catherine is quite interesting. Thanks for pointing it out.
Henry

MOST of Catherines threads are quite interesting...