Time: 0:00
Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).
This bug belongs to the mutation and copying bugs pattern
Assignment does not copy, a shallow copy still shares its contents, and mutating methods return None.
What went wrong: toFixed() returns text, not a number. Adding two pieces of text joins them.
The fix: return Number((a + b).toFixed(2));
Remember: round once, at the end. toFixed() is for display, and it gives text.
The pattern behind it: mutation and copying bugs.
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<iframe src="https://trybughunt.com/embed/7acd9272-2495-45b4-9093-8ff7223b5776" title="Debugging challenge: Adding 1 and 2 gives "1.002.00"" width="100%" height="580" loading="lazy" style="border:1px solid #d4d4d8;border-radius:12px;max-width:760px"></iframe>
<p style="font-size:14px">Debugging challenge from <a href="https://trybughunt.com/challenges/7acd9272-2495-45b4-9093-8ff7223b5776">TryBugHunt</a></p>