Question

Find the square of 39.

• A. 78
• B. 1500
• C. 1521
• D. 1530

Answer 1

The correct option is C

1521

$\text{The number 39 ends with 9.}\text{And}{9}^2=81\text{which ends with 1.}\text{Hence,}{39}^2\text{should have 1 in the units}\text{place.}$

$\text{We can observe from options that}\text{only 1521 satisfies this.}\text{Hence 1521 is the answer.}$

$\text{Alternatively, 39 should be multiplied}\text{with 39 to obtain the square.}$

$\text{So,}39\times 39=1521.$