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Hi all,

Previously i asked a questn for multiplying BIG nos (eg. 95*95, 65*65, 75*75,etc). One answerer gave a way for it.
""""
for squares of 5 (15*15, 25*25, 35*35) follow this rule
first digit * (1+first digit) then put the 25 after it.
15*15 = 1*2=2 ->225
35*35 = 3*4 = 12 ->1225
650*650 = 6*7 = 42 ->422,500
"""""""""
I thank her. Now apart from squares of 5, what are the ways for multiplying BIG nos. QUICKLY (for eg. 68*69, 76*99, 366*98, 1658*463,1532*2351, etc........................)
Pl give me a way for multiplying large nos quickly.

Thanks........

2006-09-29 20:07:01 · 4 answers · asked by Anonymous in Science & Mathematics Mathematics

4 answers

68*69=(70-1)(70-2)= 70^2 - 3*70 +2

76*99= 76*100 - 76*1

366*98=366*100 - 366*2

Basically, it's always easier to work with powers of 10 rather than the number itself. That's how I multiply quickly.

2006-09-29 23:27:38 · answer #1 · answered by Anonymous · 0 0

Hi:
Get the books; "Math Magic" By Scott Flansburg ' The Human Calculator'

How to calulate quickly

2006-09-30 11:54:48 · answer #2 · answered by Anonymous · 0 0

Have you tried a calculator? Have you tried a computer calculator with a REALLY BIG SCREEN?

2006-09-30 03:24:53 · answer #3 · answered by ye_river_xiv 6 · 0 0

111,111,111 x 111,111,111 = 12345678987654321
think about it...think about it again.......got to look good...
you prob wont understand this,,, not even with all your intellect might....

2006-09-30 03:21:38 · answer #4 · answered by aware 2 · 0 0

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