# Do not understand symbol in homework

1. Dec 4, 2011

### pantheid

My teacher, on the homework, posted what looked like a Reimman sum, except instead of a capital sigma, there was a Pi symbol instead. I never learned what that means or what its called. Can someone explain it to me?

2. Dec 4, 2011

### ArcanaNoir

Thats a product. Instead of adding like in the riemann sum, you multiply everything.

$\prod n= 1 \cdot 2\cdot \cdot \cdot \cdot$ basically. If, n was from 1 to infinity.

3. Dec 4, 2011

### D H

Staff Emeritus
It means product. Wallace's formula for pi, for example:

$$\frac {\pi} 2 = \Pi_{n=1}^{\infty} \frac {(2n)^2}{(2n-1)(2n+1)}$$