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Arithmetic Sequence Calculator

Find the nth term and sum of an arithmetic sequence, where each term changes by the same fixed amount.

Enter your values

Enter a numeric value.
Enter a numeric value.
Enter a numeric value. Use a whole number. Must be greater than zero.

Use a decimal point, without thousands separators.

Example result
Nth term
21
Sum120

The initial result uses the example values. Enter your own values and calculate again.

Edit inputs

How it works

Find the nth term and sum of an arithmetic sequence, where each term changes by the same fixed amount.

Inputs and units
Arithmetic Sequence Calculator · Inputs and units
InputExample valueWhat to enter
First term3Enter a numeric value.
Common difference2Enter a numeric value.
Number of terms10Enter a numeric value. Use a whole number. Must be greater than zero.
aₙ = a₁+(n−1)d; Sₙ = n(a₁+aₙ)/2

Worked example

Show example inputs and results

This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.

First term
3
Common difference
2
Number of terms
10

Complete example results

Nth term
21
Sum
120

Reading the result

Use quantities on the same basis. The starting value in percentage change, the denominator in a ratio and the length unit in geometry determine the meaning of the answer. Check the formula conditions alongside the example.

Questions and answers

Can I use the example values for my own calculation?

The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.

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.

Are my inputs sent to a server?

The calculator processes inputs in your browser. Its code does not send your values to a server.

Methods & accuracy

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