Question

How many times will the digit '3' appear if we write a all whole numbers from 1 to 99?

Answer 1

20

Explanation:

The number 3 will appear in the numbers 3, 13, 23, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 43, 53, 63, 73, 83, 93. In these numbers it appears 20 times.