This geometric series sum reference table shows the sum of the series for a range of first term (a) values, assuming a common ratio (r) of 3 and a number of terms (n) of 4. Every figure is computed with the same engine that powers our Geometric Series Sum Calculator, so the numbers are exact.
| First term (a) | Sum of the series | Last term |
|---|---|---|
| 0.5 | 20.0000 | 13.5000 |
| 1 | 40.0000 | 27.0000 |
| 1.5 | 60.0000 | 40.5000 |
| 2 | 80.0000 | 54.0000 |
| 3 | 120.0000 | 81.0000 |
| 4 | 160.0000 | 108.0000 |
| 6 | 240.0000 | 162.0000 |
| 10 | 400.0000 | 270.0000 |
| 14 | 560.0000 | 378.0000 |
| 20 | 800.0000 | 540.0000 |
How to use this table
Find the row closest to your first term (a) and read across to the sum of the series. For a value between two rows, the real figure sits between them — or enter your exact numbers in the Geometric Series Sum Calculator for a precise answer.
Need a value that is not in the table? — the Geometric Series Sum Calculator does it instantly, for free, with the formula and a worked example built in.
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