X and
Y are positive integers, neither of which is divisible by 10. Their product is 100,000.
What is X + Y ?
As neither X nor Y is divisible by 10 neither can have both 2,5 as a prime factore. As their prime factors must be identical with that of 10000 by the fundamental theorem of algebra, we must have that X contains all 2's and Y all 5's or vice versa.
As 100 000 = 10^5 then X=2^5 = 32 , Y=5^5 = 3125
their sum is thus 3157
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Posted by neshal
on 2004-08-02 05:57:11 |
solution
