How do you write the units when finding the area? why?

You use cm^2, in^2, etc. because you are looking for the measure of everything inside a figure (it always has to be square at the end)

For example:

Area: 14cm^2

Perimeter: 636cm

In perimeter, because you are just looking for the measure of the outside, you don't square it :)

Hope that helps, if you need any more help tell me