Smallest Positive Integer?
Algebra
Level
3
Find the smallest positive integer such that:
is divisible by 100.
18
22
24
20
25
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The sum of the first n squares is given by n(n + 1)(2n + 1)/6. If this is divisible by 100, n(n + 1)(2n + 1) = 600k. We note that 24*25 = 600, and 24 is the smallest n. Ed Gray