Calculate the highest power of 5 in 10!
Let’s see how layman will solve this question
10! can be written as:
10! = 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1
Now you have to look for numbers which contain 5 (i.e. that ends with 5 or 0)
So there are only two numbers that contain 5.
Hence the highest power of 5 in 10! is 2
This old method is time taking. We can use shortcut method to quickly solve this question
SHORTCUT METHOD
Find highest power of 5 in 127!
One can easily solve this question using shortcut method.
See the illustrations below
So, highest power of 5 in 127! is 31