Question

Find an expression for the number of colored border tiles needed for any N x N square center.

Answer 1

Answer:

8N - 4 border tiles.

Step-by-step explanation:

There are 4 border tiles in each corner and between  the tiles there are N-2 tiles along the 4 sides.

So the number of border tiles

= 4+ 4(N - 2)

= 4 + 4N - 8

= 8N - 4.