Suppose you are given a number in factorial numbers and you are asked to find number of zeros possible in that factorial.
In questions involving number of zeros, you have to find the possible combination of (2 * 5)
Find number of zeros in 6!
6! can be written as
6 ! = 6 * 5 * 4 * 3 * 2* 1
In the expression number 2 is available in bulk.
So to make process easy, only find number of 5 (which is available in limited amount)
From the expression you can easily figure out that there is only one 5.
so only one combination of (2 * 5) possible
Hence there will be only one zero in the expression