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Number theory Difficulty 5.0 AIME Find the answer
Compute the largest positive integer such that 2007n2007! is an integer.
A number or a short expression. Spacing and $ signs are ignored.
Solution
Note that 2007=32⋅223. Using the fact that the number of times a prime p divides n! is given by ⌊pn⌋+⌊p2n⌋+⌊p3n⌋+⋯ it follows that the answer is 9.
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