How it works
Find the nth term and finite sum when every term is multiplied by a constant ratio. Ratio one uses n times the first term.
aₙ = a₁rⁿ⁻¹; Sₙ = a₁(1−rⁿ)/(1−r)
Worked example
Show example inputs and result
First term: 2 · Common ratio: 2 · Number of terms: 10.
- Nth term
- 1,024
- Sum
- 2,046
Questions and answers
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
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The calculator processes inputs in your browser. Its code does not send your values to a server.
Method reviewed: October 8, 2026 · Methods & accuracy