How to make squaring numbers just a little bit easier

When a number is squared which ends in

3, the result will end in 9, which gives 

you a slight preview of the answer.

But 5 takes you 2 steps forward, because if

you square a number ending in 5, the result 

will finish off with 25. 

5 x 5 = 25

15 x 15 = 225

25 x 25 = 625

To predict what the answer will be, knock off 

5 , then enter the result in to this small formula.

n ( n + 1 )

And then add a 25 at the end .

eg. 31415 x 31415

   3141 x 3142

= 9,869,022

9,869,022 25 = 31415 x 31415

This works with any number