In many equations you can see that the variable is either subtracted or multiplied, however, in no equation will you see a variable that does not represent some form of a quantity or where it is not represented by a letter.
Using the formula : 2pi times the radius, I can plug the radius in and find the circumference. 2 times pi is 6.28, and the radius is 16. 6.28 times 16 = 100.48.
