Calculate factorials in C#

Question

How can you calculate large factorials using C#? Windows calculator in Win 7 overflows at Factorial (3500). As a programming and mathematical question I am interested in kno

Answer 1

I don't know how you could do this in a language without arbitrary precision arithmetic. I guess a start could be to count factors of 5 and 2, removing them from the product, and add on these zeroes at the end.

As you can see there are many.

>>> factorial(20000)
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