# Pi (letter)

Pi (uppercase/lowercase Π π), is the letter of the Greek alphabet, used to represent the "p" sound in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 80. Letters that came from it include the Roman P and Cyrillic П.

In mathematics, the uppercase pi is used for the Pi product operator (for example. ${\displaystyle \Pi _{i=1}^{5}i=5!}$),[1] similar to the way summation is used. The lowercase pi is used as the mathematical constant pi, also known as Archimedes's constant.[2]

## References

1. "Greek/Hebrew/Latin-based Symbols in Mathematics". Math Vault. 2020-03-20. Retrieved 2020-09-22.
2. "Pi Symbol in Greek Alphabet". www.greeksymbols.net. Retrieved 2020-09-22.