How many zeros are there in 100!? Options : 21 24 23 22

The number of zeros in 100! can be calculated by finding the number of times 10 is a factor in the numbers from 1 to 100.

10 is a product of 2 and 5. There are more factors of 2 than 5 in the numbers from 1 to 100, so we just need to count the number of times 5 is a factor.

First, divide 100 by 5. This gives 20, which is the number of multiples of 5 between 1 and 100.

Next, divide 100 by 25 (5^2). This gives 4, which is the number of multiples of 25 between 1 and 100. Each of these numbers has an extra factor of 5.

Finally, divide 100 by 125 (5^3). This gives 0, because there are no multiples of 125 between 1 and 100.

Adding these up, 20 + 4 + 0 = 24.

So, there are 24 zeros at the end of 100!.

Therefore, the correct option is 24.