If the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 are all multiplied together, how many zeros are at the end of

If the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 are all multiplied together, how many zeros are at the end of their product?

When 2 is multiplied by 5, there will be a zero at the end of their product. Also, when 10 is multiplied by any number there will be a zero at the end of their product. So there are 2 zeros at the end of the product of 1, 2, 3, 4, 5, 6, 7, 8, 9, and10.

Answer: 2

There are two factors of 5 (5 and 10 = 2*5) and so two factors of 10, thus 10! ends in two zeroes.

Note: n! ("n factorial") is the product of all of the integers from 1 through n. Also, 0! = 1 by definition.