A simple guide on how to show the circumference of a circle is π x diameter aimed at children aged between 11 and 14 ...

I am Pi, the ratio of the circumference of a circle to its diameter. Picking up the phone here at the Smithsonian, I set out to find out more about Pi and how it is represented in the national ...

Repeat the circumference- and diameter-finding until you have explored a tiny, medium, big and very large circle. Can you find a relationship that is valid for all the tested circles?

To do this, start by cutting a 3-inch piece of string to serve as the radius of the circle. What’s the radius? It’s half the diameter. Okay, but what’s the diameter?

Approximating Pi By Rick Groleau Posted 09.01.03 NOVA Around 250 B.C., the Greek mathematician Archimedes calculated the ratio of a circle's circumference to its diameter. A precise determination ...

No matter how big your circle, the ratio of circumference to diameter is the value of Pi. Pi is an irrational number---you can't write it down as a non-infinite decimal.

Let’s say we have a circle with a radius of exactly that size (or 25 billion miles in diameter) and we want to calculate the circumference, which is pi times the radius times 2.

…and you can see that the ribbon is just over 3 times the diameter of 1 circle. This number, called π (or pi), is approximately 3.14. You have shown that the circumference of a circle is π × ...