Simple Squares
A "simple square" is any integer greater than 1 that has only three positive integer factors - itself, its square root, and 1. Which of the following is a simple square?
(A) 121
(B) 100
(C) 81
(D) 64
(E) 33
Show/Hide Answer
Answer: Choice A
Level of Difficulty E M H
The square root of 121 is 11, so if the only factors or 121 are 1, 11, and 121, then 121 is a simple square by definition. The only thing left to determine is whether 121 has any other factors. With a calculator, it's fairly easy to determine that there are no others. So, the only simple square listed is 121, or choice A.
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