Math
Arithmetic Sequence Calculator
Find the nth term and the sum of the first n terms of an arithmetic sequence.
The result gives two figures: the value of the nth term and the sum of the first n terms, so the first figure is a single term in the sequence and the second figure is the total of all terms up to that point.
Formula
Nth term = a1 + (n − 1) × d. Sum of first n terms = n ÷ 2 × (2 × a1 + (n − 1) × d).
How it works
Enter the first term, the constant difference, and n. The calculator gives both the nth term and the total of the first n terms.
Worked example
For example, with a first term of 3, a common difference of 4, and n equal to 10, the 10th term is 39, and the sum of the first 10 terms is 210.
FAQs
What does the Arithmetic Sequence do?
It takes the values you enter and works out the arithmetic sequence for you, showing the result straight away.
What should I enter?
Enter ordinary numbers in the boxes above. If a value does not make sense for this calculation, the page will ask you to check it instead of showing a wrong answer.
Can I use the result for homework or everyday math?
Yes. It is a general-purpose math helper; for exam or professional work, still check the steps against your own working.
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