Math question: How many trailing zeros does 51! have?

The other day, I was studying up for job interviews and I ran across this problem. I haven't seen this before so I figured it's worth blogging.

In case you’re not familiar with the notation, 51! is pronounced 51 factorial. The factorial of a number is computed by multiplying together all the integers leading up to and including that number. For example, 4! = 1 \cdot 2 \cdot 3 \cdot 4 = 24 and 6! = 1 \cdot 2 \cdot 3 \cdot 4 \cdot 5 \cdot 6 = 720

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