Posted 13 April 2009 - 04:49 PM
Spoiler for Solution:
Given :
KOV x KOV = DEDKOV
let x = KOV => x is 3 digit number
x^2 = 1000 * DED +x
x(x-1) = 1000*DED
Now, x and x-1 are prime to each other and since 1000 (=2^3 * 5^3) is four digit number
=> Out of x and x-1 one should be of the form 8p and other 125q so that |8p - 125q| = 1
So, 3 digit multiples of 125 : 125,250,375,500,625,750,875
Now numbers 125q+1 and 125q-1 which are divisible by 8 are
376 and 624
So, 376*375 = 1000 * 141
and, 625*624 = 1000 * 390
Hence Ans : DEDKOV = 141376
This post has been edited by guru_bhai: 13 April 2009 - 04:50 PM
Perhaps the best mathematician in the world is sitting on a tree and can't even count.