Using the Number Sequence Calculator
Count the first term as term one. For an arithmetic sequence, the difference is added one fewer time than the term number. A geometric sequence uses the same counting principle with multiplication.
Worked example
Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.
Example inputs
- Sequence
- Arithmetic
- First term
- 2
- Difference or ratio
- 3
- Number of terms
- 10
Example result
- Nth term
- 29
- Sum
- 155
Method and assumptions
Arithmetic sequences add a fixed difference; geometric sequences multiply by a fixed ratio.
Check the answer in the original problem
After solving, substitute the result into the original equation or relationship where possible. This can catch a sign error or a coefficient entered in the wrong position. Keep the exact inputs available when comparing with another tool, since changing a coefficient or rounding an intermediate value can change the problem being solved.
Common question
Can a geometric ratio be negative?
Yes. A negative ratio makes signs alternate from term to term. The sum calculation includes those signs rather than adding absolute values.
Guide updated .