Question

Which is a perfect square? 72 81 90 99

Answer 1

Answer:

81 is perfect square.

Step-by-step explanation:

Given numbers  72 81 90 99 .

We have to choose the number out of given options that are perfect squares.

PERFECT SQUARES  are those numbers that be written as product of two equal numbers. Also perfect squares are those numbers that can be written as square of a number.

Thus, for given numbers

1) 72 = 8 × 9

2) 81= 9 × 9

3) 90=   9 × 10

4) 99 =  9 × 11

Thus, out of given option only 81 is written as product of two equal numbers.Thus 81 is perfect square.

Answer 2

Wouldn't it be 81?
Because 9x9=81
And that's how you get perfect squares