What percentage of numbers from 1 to 70 have squares that end in the digit 1?

What percentage of numbers from 1 to 70 have squares that end in the digit 1?

A 1

B 14

C 20

D 21

Solution

Correct Answer: Option A

Only 12= 1

92 = 81 but it is greater than 70.

So 1/70 * 100% = 1.42%