Annotate a numeric function
Difficulty: Easy
Return twice the supplied finite number.
Examples
0036-2.5-5Constraints
Use strict TypeScript and a standalone function. No imports, packages, DOM, network, or file access. Inputs are JSON-compatible with at most 1,000 elements and 100,000 characters. Do not mutate inputs. Return the specified result rather than printing. Medium tasks combine narrowing and typed transformations.
Review lesson: Inference and explicit boundariesA little nudge
Reveal one hint at a time. Give yourself a moment to try it.
Worked solution
Try your own approach first, then compare the reasoning.
Complexity
Ready when you are
Write your solution, then run it against the practice tests.
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