Mental Math Tricks by Kevin OConnor - HTML preview

5 Squared Shortcut

Here is a really quick way to square any number with a 5 on the end.

 

Let’s take

 

Ok, so what you have to do is split up the numbers, giving you

 

And

 

Forget about the for the moment and do this:

 

Always add 1, adding 1 to the 4, so we get 4 + 1 = 5

 

Then multiply this answer, 5, by the original first number, 4

 

5 X 4 = 20

 

So what you have is 20 and

 

Everyone knows = 25 right? Well it does. This is what makes it easy.

 

Put the two answers together and that's the answer!

 

2025

 

This works for any number ending in but when the numbers get over 100 it tends to get a little trickier with the multiplication.

 

Give it a try with another number.

 

Try , it isn't difficult.

 

http://www.memorymentor.com/

 

Split the numbers apart:

 

8 and

 

Again, forget about the

 

Add 1 to 8

 

8 + 1 = 9

 

Multiply 9 by the first number, which was 8

 

9 X 8 =72

 

Now, put all the numbers together, 72 and

 

= 25

 

So the answer is 7225

 

Try it out in a calculator once you have done it. http://www.memorymentor.com/