Hi I'm John. I'm maths tuter and I am secondary maths teacher. Today I am going to help you with some of the more common problems that you'll see in maths. Now a few of you may be wondering what is this thing we call Pi. Well on the principle, all this is is a letter, a greek letter for what we are using this is in maths is, it stands for very very very important number which may of you seen in the formulas involving circles. Now what is it!, what specific number is it!?. The way to think about is, any perfect circle you can find - may be on just anywhere you see on the street a clock face which ever circle - if you take that circle and you look at here. If you know the following measurments, the diameter - that's the length from the one side other side going through the origin - and you also know the distance arround the edge which you can measure by taking a piece of string pulling it arround the edges of the object and measuring that string. If you know those two things, the circumferance and distance around the edge and the diameter, then you can find out yourself exactly what Pi is . All you need to do to find out Pi is to the following. Pi is equal to with any circle that's the remarkable thing. It is circumference divided by diameter. Now you don't belive me. You go and you find yourself something is that the perfect circle and a piece of string and a roller and measure for youself. And you will find you will get it the answer about 3.1. The real value of Pi is something like 3.14. However it goes for ever. And in fact computers are still working out exacty what Pi is and always will be. So your test for this is just go around the world, find the circle and find this value so that's onece again the length arround the edge that's circumference, divided by the diameter which is the length from side to going to another through the origin and if you're putting this relationship in, you will always find Pi is the answer . And that's why its so remarkable on the wonderful number called Pi.And that's what Pi is!.