How to square any number ending in 5

Depending on how well you know your times tables, you can square and number that ends in five in you head.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• A pencil and paper to prove to you doubters that you know what you're doing.

1. Squaring a number is multiplying it times itself. So let's start with an easy one: 25 * 25.

2. Write down 25. All squared numbers ending in five have 25 as their last numbers.

3. Now, take the 2 and multiply it by the next higher number, in this case, 3.
   2 * 3 = 6.
   
   Write in down in front of the 25 so you have 625.

Tips & Warnings

• This works with any number ending in five. For example, to square 65 write down 25 and multiply 6 x 7 and write it down.
• It's 4225.
• Don't use too big a number. 125 requires you to multiply 12 x 13 and that takes a little doing.