Problem:
How many whole numbers between and do not contain the digit
Answer Choices:
A.
B.
C.
D.
E.
Solution:
There are one-digit positive integers, excluding . There are two-digit integers that do not contain the digit . There are three-digit integers that do not contain the digit . There are integers between and that do not contain the digit .
Think of each number between and as a three-digit number. For example, think of as and as . There are three-digit numbers that do not use the digit . Because does not represent a whole number between and , the total is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions