Easy big square w/0 calculator

  • #1

Main Question or Discussion Point

take any number, for example X and try and square it...

first let Y = X rounded up the nearest power, not multiple, of 10

[ X - (Y - X) ] * Y + (Y - X)^2 = X^2

it should work every time...

let X = 998

[ 998 - (1000 - 998) ] * 1000 + (1000 - 998)^2

[ 998 - 2 ] * 1000 + 2^2

996 * 1000 + 4

996000 + 4

996004

998^2 = 996004

you can do it for any number and it should work...

like 9999999999999999999999999999^2 is equal to 99999999999999999999999999980000000000000000000000000001
 

Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
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Yes, that's pretty trivial and pretty well known.
 
  • #3
Yea I figured that out out of boredem in math last year... Its neat but not practical.
 

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