Question

find the square of 39 without actual multiplication​

Answer 1

Answer:

Hence the square of 39 and 42 without actual multiplication is 1521 and 1764 respectively.

Answer 2

Answer:

Consider the given number.

39

We know that

(a−b)

2

=a

2

+b

2

−2ab

Therefore,

(40−1)

2

=(40)

2

+1

2

−2×40×1

(39)

2

=1600+1−80

(39)

2

=1521

Hence, this is the answer.