question_answer

Using contributive law, find the square of 43.

Answer:

43 = 40 + 3

So, \[{{43}^{2}}={{\left( 40+3 \right)}^{2}}\]

= (40 + 3) (40 + 3)

= 40(40 + 3) + 3(40 + 3)                                                                                                                             ½

\[=\text{ }40\times 40+40\times 3+3\times 40+3\times 3\]

= 1600 + 240 + 9

= 1849

So, \[{{43}^{2}}=1849\]