Question

find the square of the following numbers without actual multiplication
a.....64 and b......39

Answer 1

Step-by-step explanation:

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