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Pi (letter)

Greek alphabet
Α α Alpha	Β β Beta
Γ γ Gamma	Δ δ Delta
Ε ε Epsilon	Ϝ ϝ Digamma
Ζ ζ Zeta	Η η Eta
Θ θ Theta	Ι ι Iota
Κ κ Kappa	Λ λ Lambda
Μ μ Mu	Ν ν Nu
Ξ ξ Xi	Ο ο Omicron
Π π Pi	Ϻ ϻ San
Ϙ ϙ Qoppa	Ρ ρ Rho
Σ σ Sigma	Τ τ Tau
Υ υ Upsilon	Φ φ Phi
Χ χ Chi	Ψ ψ Psi
Ω ω Omega	Ϡ ϡ Sampi

Pi (upper case Π, lower case π) is the 16th letter of the Greek alphabet. In the system of Greek numerals it has a value of 80.

In Greek, the letter is pronounced 'pee'; in English, though, it is pronounced 'pie.' In words, it is pronounced /p/. In Modern Greek, the sequence of letters μπ represents the /b/ sound, as in boy (the second letter of the Greek alphabet is now pronounced /v/ as in very).

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

• The product operator in mathematics (similar to a series).
• 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:

• The mathematical constant π ≈ 3.14159, the ratio of a circle's circumference to its diameter.
• The prime counting function in mathematics.
• The elementary particle called the pi meson or pion.
• Profit in microeconomics.
• Inflation rate in macroeconomics.