What is the smallest positive integer n such that n! has exactly 10 trailing zeros?
Category: Math · Difficulty: expert
Hint: Count factors of 5 in the factorial.
Answer
25
Explanation
The number of trailing zeros in n! is given by n/5 + n/25. For n = 25, we get 5 + 1 = 6.
This is a expert math riddle — one of the harder riddles here. The answer is 25.
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