Calculate the circumference of a circle with radius of 5cm

C = 2πr

Since r = 5, you do 5 x π. Depending on whether the question is from a calculator question or not, you may need to use a calculator to multiply 5 and π.

If not, you do 5π x 2, which is 10π.

If you do use a calculator, you get 15.7079633.

15.7079633 x 2 = 31.4159266.

You will probably be asked to round this to 3 decimal places, so the answer is 31.416