Formula for the circumference of a circle = 2 • pi • radius
If diameter = 20cm
20cm divided by 2 = 10cm
The radius of the circle is 10cm, the radius is 1/2 of the diameter and is what we need to calculate the circumference.
2 • pi • 10cm = 62.8 (ROUNDED TO TENTHS PLACE)
The circumference of the circle is 62.8cm squared.