How many whole numbers less than 100 are 2-digit numbers?

Answer 1

So, you want to know how many whole numbers there are between 10-99.

Easiest way to think of this is to ask yourself, how many pages did you read if you read 10-99 inclusive? At first thought you might say 99-10=89.

So, let's look at something easier. How many pages did you read if you read 2-5 INCLUSIVE? The answer is 4, not 3.

So, 99-10+1=90.

So, there are 90 whole numbers less than 100.

Or, 99 minus 1,2,3,4,5,6,7,8,and 9 (the only single digit #'s) = 90, not counting negative numbers.