How to square a two digit number ending in 1

Hi

Let's learn to square 2 digit numbers ending in 1.

Let's multiply 31 x 31.

Multiply the numbers on the Left, 3 x 3 = 9

Multiply the numbers with each other and then double it. 3 x 1 = 3.

= 3 * 2 = 6

Multiply the numbers on the Right, 1 x 1 = 1

So your answer becomes 961.

So how about 81 x 81?

Multiply the numbers on the Left, 8 x 8 = 64

Multiply the numbers with each other and then double it,

8 x 1 = 8.

8 * 2 = 16

Multiply the numbers on the right, 1 x 1 = 1

Accommodate the 1 in 64, so that gives us 65, because your middle is a 2 Digit Number 

That's all

So the answer becomes 6561 🤯

Fun, right.

How about 91 x 91?

How cool is that 🤯