Basically Circumference = 2 * pie * radius To get the radius u need to measure the circles distance. For example I measured a circular mirror and the distance was 10cm. This is the diameter. To get the radius I’ll divide by 2 because the radius is from the centre of the circle to the edge. So, 10 divided by 2 = 5cm. The radius is 5cm. Now, Circumference = 2 * pie * r r = 5. Pie = 3.14 Circumference = 2 * 3.14 * 5 = The answer ****pie is always 3.14 I hope you understood