How many zeros does 82! have?

Answer 1

Assuming you are only interested in the zeros at the end, you basically have one zero for each of the factors (1, 2, 3, 4, 5, 6, 7, ... 82) that is a multiple of 5, since there are more multiples of 2 than multiples of 5. In other words, the number of multiples of 5 is the limiting factor.

If you want ALL the zeros, you'll have to actually calculate it, and then count them. Normal calculators are limited to about 15 significant digits, but there are some (for example, a Python calculator) that can do calculations with LOTS of digits.

82! has 19 zeros at the right hand end and 9 further 0s in between the other digits, making a total of 28 zeros.