Maths & numbers
Arithmetic sequence calculator
Find a term and partial sum of a constant-step sequence.
A clear answer. Here’s how.
The nth term is first+(n−1)×difference. The sum of the first n terms is n×(first+last)/2. Term numbering starts at 1; differences may be negative or zero.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- First term
- 3
- Common difference
- 2
- Term number / number of terms
- 10
Example result
- Requested term
- 21
- Sum of first n terms
- 120