Question

How to find the square of 31 without actual multiplication?

Answer 1

We can write 31 in the form (a+b)
=(30+1)
Now squaring it gives
(a+b) ^2= (30+1)^2
We know (a+b) ^2=(a^2+2ab+b^2)
Similarly
(30+1)^2=30^2 +2*30*1 +1^2
=900+60+1
=961