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Math

Arithmetic Sequence Calculator

Find an arithmetic sequence’s nth term, finite sum and first terms from a fixed difference.

Exact method explained belowEditable inputs

Set up your calculation

Runs on your device

SOLUTION

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter first term, common difference, number of terms.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Term n = first term + (n − 1) × common difference. The sum is n × (first term + last term) ÷ 2. Term positions start at 1.

A WORKED EXAMPLE

Starting at 3 with a difference of 4 gives 3, 7, 11, 15. The tenth term is 39 and the first ten sum to 210.

What to keep in mind

Accepts up to 1,000 terms and shows the first 20. Decimal inputs use floating-point arithmetic. This tool constructs a specified sequence; it does not infer a pattern from arbitrary data.

Common questions

Can the difference be negative?

Yes. A negative difference makes each successive term smaller. A zero difference repeats the first term.

Is the last term the same as the sum?

No. The last term is one value; the finite sum adds all requested terms.

Methodology maintained by ClarityKit. How these tools are built and checked.