How do you find number of zeros in factorial 100? - Answers

The question, as asked, is difficult to answer, The number of zeros in factorial 100 is not the same as the number of 0s at the end of factorial 100 since there will be some before the end.The answer to the second question is easy:The number of zeros is determined by the number of 10s in the factors.Since 2s are common, this, in turn, depends on the number of 5s.In 100!, there are 20 multiples of 5 each of which will contribute a 5 to the factors of 100!.In addition there are 4 multiples of 52 = 25 each of which will contribute another 5 to the factors of 100!All in all, therefore, there are 24 5s giving 24 0s at the end of 100!