Write a basic iterative Fibonacci function.

Updated Apr 28, 2026

Short answer

Use a loop to calculate numbers sequentially.

Deep explanation

The Fibonacci sequence is defined by the recurrence relation $F_n = F_{n-1} + F_{n-2}$. Use a loop to calculate numbers sequentially.

Real-world example

Modeling population growth in ideal conditions.

Common mistakes

  • Using a 1-based index when the interviewer expects 0-based.

Follow-up questions

  • What is the 5th Fibonacci number?

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