# Sigma facts for kids

Kids Encyclopedia Facts
(Redirected from Sigma (letter))
 Quick facts for kidsGreek alphabet Other letters Αα Alpha Νν Nu Ββ Beta Ξξ Xi Γγ Gamma Οο Omicron Δδ Delta Ππ Pi Εε Epsilon Ρρ Rho Ζζ Zeta Σσς 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 Ϝϝ Digamma Ⱶⱶ Heta Ϻϻ San Ϙϙ Koppa Ϡϡ Sampi Ϛϛ Stigma Ϸϸ Sho

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.

## Mathematics

The uppercase Σ is the shorthand symbol for summation (the symbol is also known as the summation operator). 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.

## Related pages

Sigma Facts for Kids. Kiddle Encyclopedia.