letter in the Greek alphabet

Sigma (uppercase/lowercase Σ σ ς) is the 18th letter of the Greek alphabet. It is used to represent the "s" sound in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 200. Letters that came from it include the Roman S and Cyrillic С.

Sigma uc lc.svg
Greek alphabet
Αα Alpha Νν Nu
Ββ Beta Ξξ Xi
Γγ Gamma Οο Omicron
Δδ Delta Ππ Pi
Εε Epsilon Ρρ Rho
Ζζ Zeta Σσ Sigma
Ηη Eta Ττ Tau
Θθ Theta Υυ Upsilon
Ιι Iota Φφ Phi
Κκ Kappa Χχ Chi
Λλ Lambda Ψψ Psi
Μμ Mu Ωω Omega
Other letters
Ϝϝ Digamma Ϟϟ Koppa
Ϛϛ Stigma Ϡϡ Sampi
Ͱͱ Heta Ϸϸ Sho
Ϻϻ San


The uppercase Σ is the shorthand symbol for summation (the symbol is also known as the summation operator).[1] It is often used to condense Taylor series and to write out trigonometric functions such as sine, cosine, and tangent as series.

The lowercase σ is used to represent population standard deviation in statistics, and permutation function in abstract algebra.[1][2]

Related pages


  1. 1.0 1.1 "Greek/Hebrew/Latin-based Symbols in Mathematics". Math Vault. 2020-03-20. Retrieved 2020-10-07.
  2. "Sigma Symbol in Greek Alphabet". Retrieved 2020-10-07.