# How is the number Pi, derived?

1. Mar 5, 2010

### ruko

How is the number 3.14159..........etc, derived? I know it has been calculated out to very great lengths and I'm wondering how it's done.

2. Mar 5, 2010

3. Mar 6, 2010

### MWIGuy

Re: Pi

Just find the proportion of radius to circumferance, I believe. I know it is some kind of proportion.

4. Mar 6, 2010

### Unit

Re: Pi

My personal favourite:

$$\frac2\pi = \frac{\sqrt2}2 \cdot \frac{\sqrt{2+\sqrt2}}2 \cdot \frac{\sqrt{2+\sqrt{2+\sqrt2}}}2 \cdot \cdots\!$$

5. Mar 6, 2010

### hotvette

Re: Pi

Modern calculation of pi no doubt use infinite series, first formulated in Newton's time (mid 1600's). Archimedes used circumscribed polygons w/ 96 sides to calculate pi with three digit accuracy.