Arithmetic Sequence Calculator
Find a term and partial sum of an arithmetic sequence.
Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
Example Calculation
- First term: 3
- Common difference: 4
- Term number: 5
For 3, 7, 11, 15, 19, the fifth term is 19 and the sum is 55.
Frequently asked questions
How do I use this calculator?
Enter first term, common difference, term number. The result updates automatically. Use Reset to restore the example values.
What method does it use?
aₙ = a₁ + (n−1)d; Sₙ = n(a₁+aₙ)/2. Follow the units and definitions shown with the inputs to apply this relationship consistently.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.