Quickly square any number ending with 5

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If you come across a number ending with five and you really need to square it, don't worry, there's an easy way.

First, just think of the number as n5 (this does not mean n x 5), where n is every number before the five. To get the square, write 25 and in front of that write n x (n + 1).

As an example:
Say your number is 65 squared. 
6 x 7 = 42
42 
    >4225
25 

Your answer is 4225.

 Your's in numbers,
Lachlan

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