Arithmetic Sequence Calculator
Fill in the values and the answer updates as you type.
How the Arithmetic Sequence Calculator works
The nth term is a1 + (n − 1) × d. The sum is n × (first + last) ÷ 2. Example: 3, 7, 11, … with 10 terms ends at 39 and adds up to 210.
Inputs and results
The Arithmetic Sequence Calculator takes 3 inputs and gives 3 results.
What you enter
- First term — starts at 3.
- Common difference — starts at 4.
- Number of terms — starts at 10.
What you get
- Last (nth) term
- Sum of all terms
- Average of terms
Example: Arithmetic Sequence Calculator with the starting values
With first term 3, common difference 4 and number of terms 10, the calculator returns:
| Last (nth) term | 39 |
|---|---|
| Sum of all terms | 210 |
| Average of terms | 21 |
Change any value above and the results update straight away.
Arithmetic Sequence Calculator FAQ
How do I use the Arithmetic Sequence Calculator?
Enter first term, common difference and number of terms in the fields, then read last (nth) term, sum of all terms and average of terms in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Arithmetic Sequence Calculator calculate?
Nth term and sum of an arithmetic sequence. It returns last (nth) term, sum of all terms and average of terms from the 3 values you provide.
What values does the Arithmetic Sequence Calculator start with?
It opens with first term 3, common difference 4 and number of terms 10 so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Arithmetic Sequence Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Arithmetic Sequence Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.