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HomemathSeries Sum

Series Calculator — Sum a Series from n Start to End

Sum mathematical series from any start to end value. Supports expressions with n, exponents, and common mathematical functions.

✓ Formula verified: January 2026
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Series Sum

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The Formula

S = Σ_{n=start}^{end} f(n)

The series calculator computes the sum of a mathematical sequence from a start index to an end index. For each integer value of n from start to end, the expression f(n) is evaluated and all results are added together. This is denoted by the capital Greek letter Sigma (Σ), which represents summation. The lower bound (n = start) and upper bound (end) define the range of summation.

Variable Definitions

n

Summation Index

The integer variable that takes each value from start to end during summation.

start

Lower Bound

The first integer value of n at which the expression is evaluated.

end

Upper Bound

The last integer value of n at which the expression is evaluated.

f(n)

Expression

The mathematical formula evaluated at each n, defining the sequence terms.

S

Sum

The total sum of all terms from n = start to n = end.

How to Use This Calculator

  1. 1

    Enter the starting value (n start) and ending value (n end) for the summation index.

  2. 2

    Write the expression using n as the variable. Use ^ for exponents (e.g., 2^n, n^2).

  3. 3

    Use pi for the mathematical constant π. The calculator supports basic arithmetic operators and parentheses.

  4. 4

    View the total sum, the first 20 terms in the series, the number of terms, and the last term value.

  5. 5

    The expression is safely evaluated for each integer n in the range. Invalid or non-finite terms are skipped.

Quick Reference

FromTo
Sum of constantsΣ c = c × (b − a + 1)
Sum of nΣ n = b(b+1)/2 − (a−1)a/2
Geometric seriesΣ r^n = (r^(b+1) − r^a)/(r − 1)
Harmonic termsΣ 1/n diverges as n → ∞

Common Applications

  • Computing the total accumulated value of a sequence, such as the sum of the first N integers or squares.
  • Evaluating finite approximations of infinite series to estimate the value of convergent series.
  • Calculating partial sums of arithmetic and geometric progressions in financial mathematics.
  • Analyzing the behavior of series by examining how partial sums grow as more terms are added.
  • Computing discrete approximations of integrals using Riemann sums where f(n) represents sampled values.

A series sums the terms of a sequence from a starting index to an ending index

Understanding the Concept

A series is the sum of the terms of a sequence. The notation Σ_{n=a}^{b} f(n) means "evaluate the expression f(n) for each integer n starting at a, ending at b, and add all the results together." Series are fundamental in mathematics and appear throughout calculus, number theory, and applied mathematics. Finite series have a definite number of terms and always yield a finite sum. Common examples include arithmetic series (where consecutive terms differ by a constant), geometric series (where consecutive terms have a constant ratio), and harmonic series (terms of the form 1/n). The series calculator can handle any expression using standard arithmetic operations, exponents, and the constant π. By varying the expression and bounds, you can explore a wide range of mathematical series — from simple sums of consecutive integers to more complex sequences involving powers and reciprocals.

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