What is the advantage of using exponential notation?

The advantage of using exponential notation is that you won't have to keep writing a long number
For example, 40,000,000,000,000 would be tedious to write over again, but using exponential notation that number would be just 4 X 10^13.

Ido not know i use to

5\16 x 2\5 = 10/80simplify to 1/80