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 ...

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 dimensions of the Earth was first measured by Greek philosopher Eratosthnes in 200 B.C. by using simple geometric methods. He dug a narrow well at Syene (now Aswan). The well would reflect the ...

Look at the slices in the circle - each slice is "r," the radius, long on a side. Here is what we know before we start: The circumference of the circle is Pi times the diameter. And the diameter is 2 ...