Answer:
C = 2πr.
Explanation:
To calculate the circumference of a circle, use the formula C = πd, where "C" is the circumference, "d" is the diameter, and π is 3.14. If you have the radius instead of the diameter, multiply it by 2 to get the diameter. You can also use the formula for circumference of a circle using radius, which is C = 2πr.