Which of the following numbers is different from the rest?
Show answer & explanation
Correct answer: D
Explanation
121: This number is the perfect square of 11 → (11 × 11 = 121)
144: This number is the perfect square of 12 → (12 × 12 = 144)
169: This number is the perfect square of 13 → (13 × 13 = 169)
172: This is not the perfect square of any integer. (The square of 13 is 169, and the square of 14 immediately following it is 196).
All other numbers (121, 144, 169) are perfect squares, while 172 does not follow this rule. Therefore, this number is different from all the others.
The correct answer is 172.