Question

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

• A. 20 %
• B. 25 %
• C. 15 %
• D. 16 %

Answer 1

The correct option is A 20 %

The numbers from 1 to 70 that have their squares ending in digit 1 are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69 i.e. 14 in numbers
$\therefore$ Required percentage $=\frac{14}{70}\times 100=20\%$