#troubleshooting

I have a bug in my Python code. The function is supposed to calculate the factorial of a number, but it's returning an incorrect result for inputs greater than 5. Here is the code: [paste code here]. Help me find and fix the bug.

Generate a comprehensive troubleshooting guide. Format: 1. Common symptoms/problems listed clearly. 2. Step-by-step diagnostic questions. 3. Simple solutions for each issue. 4. Visual aids or diagrams where helpful. 5. 'If this doesn't work' escalation path. 6. Safety warnings if applicable. 7. When to contact support. 8. Video tutorial links. Use numbered steps, clear language, and avoid technical jargon.

Troubleshoot promo code issues. Checklist: 1. Verify code spelling and case sensitivity. 2. Check expiration date. 3. Confirm minimum purchase requirements. 4. Verify eligible products/categories. 5. Check for one-time use restriction. 6. Ensure not combining with other offers. 7. Manually apply if valid but system error. 8. Offer alternative discount if code expired. Resolve quickly to prevent cart abandonment.