Question

Find the square of $43$ without doing actual multiplication.

Answer 1

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> ${43}^2$=${(40+3)}^2$= $40(40+3)+3(40+3)$
= ${40}^2$ +$40\times 3+3\times 40$ + $3^2$
= $1600+120+120+9$
= $1849$.