Problem:
Assume every -digit whole number is a possible telephone number except those which begin with . What fraction of telephone numbers begin with and end with
Answer Choices:
A.
B.
C.
D.
E.
Solution:
There are digits. Excluding and leaves digits. Thus of all telephone numbers begin with . Of these, end with giving which begin with and end with .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions