We are roofing our house . We know the basic idea of measuring to get the sqare footage of the roof but have come up with numbers that don't make sense... Anybody ? Help!

A squared X B squared = C squared.

Measure the width of the house, divide by 2 to get Run. The Run will be A.
Measure from a horizontal line between the eaves to the peak to get Rise. Rise will be B.
So the Run squared times the Rise squared will give you the roof surface squared. The roof squared will be C.

Find the square root of the roof squared (C).
Multiply by 2. You have to do front and back.
Multiply that number by length to find the square footage of roof.

In shingle speak, a square is 100 square foot. Three (3) bundles make a square.