Squaring of a number ending with 5

Squaring a number is simply multiplying a number by itself

To find the square of a two-digit number ending in 5, multiply the tens digit “By one more than the one before” or by the next number. 

Then suffix the product of 5 x 5, or 25

Example: Find 45²

a. To get the first part, multiply the tens digit, 4, by the next higher number, which is 5.

4 x 5 = 20

b. The second part is always 25.

So, 45² = 2025