Calculating squares on a grid.

In Math we were shown by our Math teacher a 10 by 10 grid. The grid wasn't really 10 by 10. What I mean by that is that each corner side you're counting twice when really it's only really meant to be counted once.

So the top is 10 and bottom is 10 and the sides are 8 as if the sides were 10, it would mean you were counting the sides twice.

So this is a little blog post about how to calculate the squares on a grid (10 by 10)

In First base we have to find out how much numbers are on the outline of the border of the grid, For a 10 by 10, it's 36.

So we have that down all we need to do is find an easy calculation for it.

A simple way to do it is
10 + 8 + 10 + 8 = 36
So 10 from the top and bottom and the two 8 at the sides, add them together to get 36.

If we covert the numbers algebra wise then the 10 would be the single n and the 8 would be the (n-2)
which Gives us our calculation like above but in letters and numbers.

n + (n - 2) + n + (n - 2) = 36

(Bonus)
That is simple algebra when it comes to time tables we use algebra like this
Normal - 4 x 8 + 4 = 36
Algebra - 4 (n - 2) + 4 = 36
Just doing the same before with the eight converting it into an (n - 2) and leaving the 4 as a 4.

(Can you think of any other ways of doing a grid finding the answer and converting it into algebra?)