Type Inference

function add(a: number, b: number) {
	return a + b // TypeScript knows this returns number
}

// ❌ Error: Parameter 'a' implicitly has 'any' type
function add(a, b) {
	return a + b
}

// ✅ Correct
function add(a: number, b: number) {
	return a + b
}

1. Hover over multiply and notice TypeScript infers its return type as number without an annotation
2. On divide, add an explicit return type of : number so TypeScript flags the buggy string return
3. Fix divide so dividing by zero throws an Error with the exact message "Cannot divide by zero" (instead of returning a string)
4. Create isEven(n: number) that returns whether n is even; let TypeScript infer the boolean return type
5. Export multiply, divide, and isEven

Required exports

Completion criteria

• multiply(4, 5) → 20 (and other products work)
• divide(10, 2) → 5; divide(7, 2) → 3.5
• divide(10, 0) throws with message "Cannot divide by zero"
• isEven(4) / isEven(0) → true; isEven(7) → false