The circumference of a circle is the distance around the shape. The ability to round a number to a number of decimal places or to a number of significant figures means that answers can be written to ...

The radius of a circle or a sphere is the distance between the center and the edge. The radius can be used to calculate a circle's diameter, area and circumference. Likewise, a sphere's volume is ...

Here's a funny story. A reporter at National Geographic wanted to find someone to interview about pi—that number you learned in grade school that is the ratio between a circle's circumference and its ...