How do you find the circumference of a circle with a diameter of 4.4 cm?

Use the formula ##c=pid## to obtain circumference ##~=13.823##

The constant ##pi## is the ratio of the circumference of a circle to its diameter (i.e. ##pi = c/d##) or more commonly ##c =pi*d## (where ##c## is the circumference and ##d## is the diameter).

You can use a calculator to evaluate this (if your calculator does not have the constant ##pi## assigned to a button, you can use ##3.14159## which is a reasonable approximation for virtually all situations)