Geometric Sequence Calculator
Use the Geometric Sequence Calculator for a transparent, instant calculation with validated inputs and cited sources. For a query such as “geometric sequence formula”, enter the matching values and units below and review the stated assumptions.
How to use this calculator
Enter the requested values and units.
Review the assumptions and any warnings shown with the result.
Use the result together with the cited source and your real-world requirements.
Formula
The nth geometric term is aₙ = a₁ × r^(n − 1); the sum is a₁(1 − rⁿ)/(1 − r), or a₁n when r = 1.
Worked example
Worked example: Inputs: First term: 2; Common ratio: 3; Term number: 5. Outputs: Nth term: 162; Sum through nth term: 242.
Assumptions and limits
- The result depends on the values, units, and assumptions entered. It does not infer missing context.
Sources
- OpenStax, Rice University: Precalculus 2eReference material reviewed for the stated method, units, or domain. Confirm that its scope matches your use case. Reviewed 2026-08-14.
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Frequently asked questions
How does the Geometric Sequence Calculator work?
The nth geometric term is aₙ = a₁ × r^(n − 1); the sum is a₁(1 − rⁿ)/(1 − r), or a₁n when r = 1.
What should I enter?
First term, Common ratio, Term number
What should I verify?
Review the assumptions and any warnings shown with the result. The result depends on the values, units, and assumptions entered. It does not infer missing context.
Last updated 2026-08-14 · math-geometric-sequence-v1 · opportunity-content-2026-08-14 · Trusty Calculator Editorial Team