When I was 8 years old. I see a little logic behind this which improves my speed in this type of questions.

For this first square the **smaller no**.(if you don’t Know how to get square many technics are here)

And **double it**.

Example - 12 * 24

12^2 * 2(it can done simply in mind)

144 * 2 = 288

Example - *48 * 96 = 2304 * 2 = 4608*

Example - *57 * 114 = 3249 * 2 = 6498*

I hope you understand it.If you do it with my logic you can do this very quickly.