Fibonacci Number Calculator

Fibonacci Number Calculator

Takes one integer N from 0 through 10000; default input is 10. It generates N terms beginning 0,1,1,2,... and shows the last generated term plus a preview. The displayed Nth term is F(N-1) under conventional zero-based F(0)=0 indexing, not F(N). N therefore counts generated terms.

For example, N=10 gives last term 34 and preview 0,1,1,2,3,5,8,13,21,34. N=0 returns 0 as a special result with an empty sequence. N=1 returns 0. The recurrence is next=a+b with initial a=0,b=1, using BigInt for exact integers rather than floating-point approximations.

Only the first 200 terms are displayed; N>200 adds an ellipsis while the last term is still calculated exactly. It does not export all 10000 terms or draw a graph. Implementation retains only the preview and running terms instead of the whole large sequence.

Empty, fractional, negative, above-limit and multiple parsed numeric inputs are rejected. Enter a plain integer without grouping to avoid ambiguity; the shared locale number parser may normalize localized digits, but there is no numeral-system selector. Output digits are exact integer strings, and preview uses comma-space separators rather than a locale-specific CSV format.

Local browser calculation with no upload or AI. Press the calculation action after changing N; Clear resets input/result. On mobile test N=10 first and expect a long final integer at large N. This is a sequence calculator, not a prediction model, financial signal or guarantee of a golden-ratio layout.