Q1.
Find the following products. (a) 4 × (– 3) (b) (– 6) × (– 3) (c) (– 5) × (– 1) (d) (– 8) × 4 (e) (– 9) × 10 (f) 10 × (– 17)
Answer
Multiply the magnitudes, then fix the sign by counting negatives.
(a) 4 × 3 = 12, one negative → –12
(b) 6 × 3 = 18, two negatives → 18
(c) 5 × 1 = 5, two negatives → 5
(d) 8 × 4 = 32, one negative → –32
(e) 9 × 10 = 90, one negative → –90
(f) 10 × 17 = 170, one negative → –170
(b) 6 × 3 = 18, two negatives → 18
(c) 5 × 1 = 5, two negatives → 5
(d) 8 × 4 = 32, one negative → –32
(e) 9 × 10 = 90, one negative → –90
(f) 10 × 17 = 170, one negative → –170
| Product | Signs | Answer | |
|---|---|---|---|
| (a) | 4 × (–3) | different | –12 |
| (b) | (–6) × (–3) | same | 18 |
| (c) | (–5) × (–1) | same | 5 |
| (d) | (–8) × 4 | different | –32 |
| (e) | (–9) × 10 | different | –90 |
| (f) | 10 × (–17) | different | –170 |
Why it happens: part (c) is worth a second look. Multiplying by –1 keeps the magnitude at 5 and only flips the sign, so (–5) × (–1) = 5. That is the rule –1 × a = –a in action.