Question

find the square of the following Number without actual mulltplication.

(1)39
(2)42​

Answer 1

39^2=(30+9)^2=30(90+9)+9(30+9)

= 30^2+30×9+9×30+9^2

= 900 +270 +270 +81 =1521

$\rule{300}{2}$

42^2 =(40+2)^2=40(40+2)+2(40+2).

=40^2+40×2+2×40+2^2.

=1600 + 80 +80+4 =1764

#answerwithquality #bal

Answer 2

Answer:

39^2 = (30 + 9)^2 = 30(30 + 9) + 9(30 + 9)

= 30^2 + 30 * 9 + 9 * 30 + 9^2

= 900 + 270 + 270 +81

= 1521

42^2 = (40 + 2)^2 = 40(40 + 2) + 2(40 + 2)

=40^2 + 40 * 2 + 2 * 40 + 2^2

= 1600 + 80 + 80 + 4

=1764