2002 AMC 8 Problems/Problem 19

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Problem

How many whole numbers between 99 and 999 contain exactly one 0?

$\text{(A)}\ 72\qquad\text{(B)}\ 90\qquad\text{(C)}\ 144\qquad\text{(D)}\ 162\qquad\text{(E)}\ 180$

Solution

This list includes all the three digit whole numbers except 999. Because the hundreds digit cannot be 0, there are $2$ ways to choose whether the tens digit or the ones digit is equal to 0. Then for the two remaining places, there are $9$ ways to choose each digit. This gives a total of $(2)(9)(9)=\boxed{\text{(D)}\ 162}$.

See Also

2002 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 18
Followed by
Problem 20
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All AJHSME/AMC 8 Problems and Solutions