Question

Which of the following is NOT a perfect square?
144
124
81
121
64

Answer 1

124

Answer 2

124

Answer 3

144 = 12 squared
81 = 9 squared
121 = 11 squared
64 = 8 squared

Answer 4

If you can take the square root of a number and it comes out a whole number then it is a perfect square.

Answer 5

sqrt(144) = 12
sqrt(81) = 9
sqrt(121) = 11
sqrt(64) = 8
sqrt(124) = 11.13552873

Answer 6

\[ \sqrt{124} = 2\sqrt{31} \] which is non-integer (irrational number) hence 124 is not a perfect square.