Consider Here the number is 25. We have to find out the square of the number. For the number 25, the last digit is 5 and the ‘previous’ digit is 2. Hence, ‘one more than the previous one’, i.e. 2+1=3. The formula, in this context, gives the procedure to multiply the previous digit 2 by one more than it self, that is, by 3.

It becomes the L.H.S (left hand side) of the result.

**i.e. 2 X 3 = 6.**

The R.H.S (right hand side) of the result is , that is, 25.

Thus,

and 25 = 625

In the same way,

and 25 = 3*4 and 25 = 1225

and 25 = 6*7 and 25 = 4225

and 25 = 10*11 and 25 = 11025

and 25 = 13*14 and 25 = 18225