Infinity Symbol (∞)
Mathematical symbol representing an unbounded quantity or the concept of endlessness.
Mathematical/Western · 1655 – present
Summation Sign (Σ)
Greek capital letter Sigma used as the mathematical symbol for summation.
Description
The capital Greek letter Sigma (Σ) was adopted as the mathematical summation symbol by Leonhard Euler in 1755 in his 'Institutiones calculi differentialis'. It denotes the sum of a sequence of terms, typically written with an index variable below and an upper limit above the symbol. The notation Σᵢ₌₁ⁿ aᵢ means the sum of all terms aᵢ for i from 1 to n. The symbol is fundamental in statistics, probability theory, and all branches of mathematics involving series.
Origin & Cultural Context
Adopted as a summation symbol by Leonhard Euler in 'Institutiones calculi differentialis' (1755).