Fibonacci calculator
Compute the nth Fibonacci number F(n) and the sum of the first n terms.
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Tool guide
Fibonacci calculator: how it works
Practical information to understand the result and use this tool correctly.
About Fibonacci calculator
Fibonacci numbers satisfy F(n)=F(n−1)+F(n−2) with F(0)=0, F(1)=1.
The partial sum identity Σ F(k) from 0 to n equals F(n+2)−1.
Appears in algorithms, phyllotaxis models, and combinatorics.
How to use it
- 1Enter n ≥ 0.
- 2Read F(n) and the sum.
- 3Prefer n ≤ 70 for exact integer display.
Frequently asked questions
- F(0) or F(1) start?
- This tool uses F(0)=0, F(1)=1.
- Large n?
- Beyond ~70, JavaScript uses floating-point approximation.