A circle has a diameter of 40 inches. What is the circumference? Write your answer using pi

Question

I know the answer is 125.6, but I don't have an idea of how to write it using pi.

Answer 1

The definition of π is the ratio of the Circumference of a circle to its Diameter,   π=C/d.

    That's why we can write:    C=πd

 

If d=40, then what is C?

   C = 40π       (we usually write numbers first)