Number Sequence Solver
Enter an observed number sequence to see every supported rule that fits, the next value, and an ambiguity note.
A QUICK WALKTHROUGH
How to use this tool
- Enter 3 to 12 finite numbers separated by commas or whitespace.
- Find matching arithmetic, geometric, and Fibonacci candidates.
- Review the rule explanation before copying a next value.
Geometric term and finite sum
For a matching geometric rule, optionally enter n from 1 to 10,000 to calculate aₙ = a₁ r^(n−1) and the first n terms’ sum from the first observed term. Leave n blank to show only candidates. If rules overlap, confirm the geometric rule first. Ratios 1 and −1 are handled separately. Results only extrapolate observed terms and do not guarantee future behavior.
Three explicit rules
The solver checks constant difference, constant ratio, and the Fibonacci rule where each term is the sum of the previous two.
Ambiguity is visible
Short sequences can fit more than one rule. Every matching candidate is shown instead of pretending that one prediction is universally correct.
Bounded local processing
Input is limited to 3–12 finite numbers. Parsing, matching, and copying happen in your browser; input is not uploaded or stored.
GOOD TO KNOW
Common questions
Which patterns are checked?
Arithmetic, geometric, and Fibonacci patterns only.
Can a sequence have multiple answers?
Yes. The tool lists every supported rule that matches the observed terms.
Does it use a remote service?
No. The solver runs locally in your browser.