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 ...

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 ...

Now for the important part. Today, as you may know, is Pi Day. Why today? Because it’s March 14—yes, 3/14—and 3.14 is the value of pi to two decimals. Of course, the actual number continues to an ...

Happy pi day! The date 3/14 is, of course, a poor approximation for π, which has infinite digits (3.1415926...). But that raises a few questions: How many digits have we actually found? And how many ...

So you have a circle. What is the area of that circle? Surely everyone remembers that the area of a circle is: Where Pi (π) is of course the number and r is the radius of the circle. Where does this ...

Introduction If you wanted to measure the circumference of Earth, how long would your tape measure have to be? Would you need to walk the whole way around the world to find the answer? Do you think ...

Imagine a piece of string wrapped around the Earth's equator - that's about 40,000km. How much MORE string would you need for it to sit 15cm above the ground, all the way around? The important thing ...