SERIESSUM Function in Excel: Sum of a Power Series

SERIESSUM Function in Excel: Sum of a Power Series 1
⏱ 1 min readUpdated 5 October 2026

Maths & trigLevel: ExpertAvailable in: Excel 2007+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. SERIESSUM in practice
  5. Where you will use it
  6. Worked example
  7. Mistakes people make
  8. Related functions

SERIESSUM adds a power series a1·x^n + a2·x^(n+m) + …, e.g. to approximate e^x or sin(x) with a few terms.

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Syntax

=SERIESSUM(x, n, m, coefficients)
Argument What it means
x Input value
n First power
m Step between powers
coefficients a1, a2, …

Examples

Example 1

=ROUND(SERIESSUM(A2,0,1,{1,1,0.5,0.1666667,0.0416667}),5)

Result: 2.70833. See the worked example table below for more cases.

SERIESSUM in practice

Where you will use it

  • Approximating e^x or sin x
  • Polynomial models
  • Numerical methods teaching

Worked example

xFormulaResult
1=ROUND(SERIESSUM(A2,0,1,{1,1,0.5,0.1666667,0.0416667}),5)2.70833
0.5=ROUND(SERIESSUM(A3,0,1,{1,1,0.5,0.1666667,0.0416667}),5)1.64844
2=ROUND(SERIESSUM(A4,0,1,{1,1,0.5,0.1666667,0.0416667}),5)7

Results calculated in Excel. First 5 terms of the series for e^x: compare with EXP(x).

Mistakes people make

MistakeWhat to do instead
Too few termsApproximation drifts for large x
Coefficients as textUse numbers

EXP · SUMPRODUCT

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