Squaring a 2 digit number

The basis of this short cut to find a square of any 2 digit no is the algebraic equation

(a+b)^2 = a^2 + 2ab + b^2

For eg : If the no 43 has to be squared, then
(40+3)^2 = 40^2 + 2*40*3 + 3^2

Since the first part 40^2 can be easily resolved, adding up of the RHS of the equation gives the resultant.
I believe an addition always comes to aid better than a multiplication in the last few crucial moments of the exams !