Add the lengths of all sides of the shape
Use the correct formula for the shape if it has one
For a rectangle, use P = 2(length + width)
For a square, use P = 4 × side
For a triangle, use P = side1 + side2 + side3
For a circle, use circumference = 2πr or πd
Make sure all measurements are in the same unit
Write the final answer with the correct unit