Problem:
What is the value of 169(2112−2021)2?
Answer Choices:
A. 7
B. 21
C. 49
D. 64
E. 91
Solution:
Observe that 2112−2021=91=7⋅13 and that 169=132. Thus
169(2112−2021)2=132(7⋅13)2=72=(C)49
The problems on this page are the property of the MAA's American Mathematics Competitions