Question

Find the square of number $39$ without actual multiplication.

• A. $1521$
• B. $1625$
• C. $1574$
• D. $1624$

Answer 1

The correct option is A $1521$

$39=40-1$
${39}^2=(40-1{)}^2$
$=1600+1-80$
$=1521$