How do you convert rectangle length to PM?

Answer: First of all, in order to begin the process, you need to know

what "PM" means. Quite frankly, that lets me out.

Answer: If you mean perimeter: You have to add the length of all four sides. In other Words, twice the length + twice the width, or 2 x (length + width). If you only know the rectangle's length, you simply don't have enough information.