Squaring Numbers that End in 5

There is a simple trick to squaring numbers that end in 5, and it works no matter how large your number is!

Your first step when squaring a number that ends in 5 is to take the first digit of said number and multiply it by the number that comes after it. For example we'll use the number 45.

So, your first digit in 45 is 4

The number that comes after 4 is 5 so...

4x5=20

Now after you do that step you simply add 25 to the end of that number.

Therefore, 45^2= 2025