Problem:
What is the value of 9!11!−10!​?
Answer Choices:
A. 99
B. 100
C. 110
D. 121
E. 132
Solution:
9!11!−10!​=9!10!⋅(11−1)​=9!10⋅9!⋅10​=100​
The problems on this page are the property of the MAA's American Mathematics Competitions