Quick calculations with identities

Identities turn big multiplications into small ones. You will write two of them as functions and use them on numbers near $100$.

The idea. For $n = b + k$: $n^2 = b^2 + 2bk + k^2$. For two numbers equally far from $b$: $(b - k)(b + k) = b^2 - k^2$.

Your tasks.

1. In square_near, return $n^2$ using $b^2 + 2bk + k^2$, with $k = n - b$.
2. In product_near, return $(b - k)(b + k)$ using $b^2 - k^2$.
3. Fill results with square_near(97, 100), product_near(100, 9) and square_near(1004, 1000).