What is the square root of 239,121?

[BTGmoderatorDC]

What is the square root of 239,121?

(A) 476
(B) 489
(C) 497
(D) 511
(E) 524


OA B

Source: Veritas Prep

[Scott@TargetTestPrep]

What is the square root of 239,121?

(A) 476
(B) 489
(C) 497
(D) 511
(E) 524


OA B

Solution:

When calculating the square root of 239,121, we must remember that we are looking for a number such that when it’s multiplied by itself (or squared) it produces a units digit of 1 (since 239,121 has a units digit of 1).

Of our answer choices, the only two numbers that will produce a units digit of 1, when squared, are 489 and 511.

However, because 500^2 = 250,000, we see that 511^2 > 250,000, whereas 489^2 < 250,000. Thus, the square root of 239,121 must equal 489.

Answer: B