Pi (letter)

Pi (Π π) is the 16th letter of the Greek alphabet and has a numeric value of 80.

The upper-case letter Π is used as a symbol for:

• In mathematics, the product operation.
• In textual criticism, Codex Petropolitanus, a 9th century, uncial codex of the Gospels, now located in St. Petersburg, Russia.

The lower-case letter π is used as a symbol for:

• In economics, profit.
• In mathematics, the constant pi, which is the ratio of the circumference to the diameter of a circle.
• In number theory, the function π(x) is the number of primes that are less than or equal to x.
• In particle physics, π⁰, π⁺ and π^- are three forms of pi meson.

See also Pi (movie)