Bunuel wrote:
For positive integers a and b, the remainder when a is divided by b is equal to the remainder when b is divided by a. Which of the following could be a value of ab ?
I. 24
II. 30
III. 36
A. II only
B. III only
C. I and II only
D. II and III only
E. I, II, and III
The only way the remainder when a is divided by b is equal to the remainder when b is divided by a is a = b since then the remainder in both cases is 0. That is, if a = b, a/b = 1 R 0 and b/a = 1 R 0.
Since a = b, we see that ab must be a perfect square. So only III could be a value of ab.
Answer: B
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83% (01:21) correct 
