Problem:
What is 10⋅(21​+51​+101​)−1 ?
Answer Choices:
A. 3
B. 8
C. 225​
D. 3170​
E. 170
Solution:
Note that
10⋅(21​+51​+101​)−1=10⋅(108​)−1=225​​
The problems on this page are the property of the MAA's American Mathematics Competitions