Squaring a number that ends in 5 is very easy.
This method can be applied to any number of the form: 15, 25, 35, …., 95, 105, 285, …. and so on.
Sutras:
- By One More Than the One Before
Let’s explore this with an example:
352 → 3•4 / 25 → 12 / 25 → 1225
The result is comprised of two “parts”.
The bottom “part” is always 25.
The top “part” is n(n+1).
More examples as below:
752 → 7•8 / 25 → 56 / 25 → 5625
452 → 4•5 / 25 → 20 / 25 → 2025
952 → 9•10 / 25 → 90 / 25 → 9025
1152 → 11•12 / 25 → 132 / 25 → 13225
Maths is Fun and Easy 