Problem:
The hundreds digit of a three-digit number is more than the units digit. The digits of the three-digit number are reversed, and the result is subtracted from the original three-digit number. What is the units digit of the result?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Take as the original number, and subtract . The difference is and the units digit is . The same result will be obtained with any number that meets the criteria.
The original number is , with . The reversed number will be . The difference is . So the units digit is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions