Higher November 2019 Paper 2 Q5
5 Work out the lowest common multiple (LCM) of 120 and 144 [2 marks]
| Answer | Mark | Comments |
|---|---|---|
| 720 | B2 | B1 at least 3 multiples of 120 (> 120) and at least 3 multiples of 144 (> 144) eg 240 360 480 and 288 432 576 or (120 =) \(2 \times 2 \times 2 \times 3 \times 5\) or (144 =) \(2 \times 2 \times 2 \times 2 \times 3 \times 3\) or (Answer =) \(2 \times 2 \times 2 \times 2 \times 3 \times 3 \times 5\) or (Answer =) \(2^4 \times 3^2 \times 5\) or (Answer =) any multiple of 720 (> 720) eg 1440 or 17 280 |
Additional guidance
| Prime factor responses for B1 may be in index form eg (120 =) \(3 \times 5 \times 2^3\) | B1 |
| Prime factor responses for B1 may be seen on a factor tree or a Venn diagram or in repeated division eg1 2 2 2 3 5 on a factor tree for 120 eg2 2 2 2 2 3 3 inside one circle on a Venn diagram | B1 B1 |
| For B1 allow some incorrect multiples if 3 correct of each eg1 240 380 480 720 900 (3 correct) and 288 432 576 868 (3 correct) eg2 Answer 1440 but some incorrect multiples seen | B1 B1 |
| Any multiple of 720 (> 720) given in unsimplified form eg1 \(2^7 \times 3^3 \times 5\) eg2 \(2 \times 2 \times 2 \times 2 \times 2 \times 5 \times 3 \times 3\) | B1 B1 |
| B1 can still be awarded even if subsequently works out HCF | |
| Answer 720 with some incorrect multiples seen | B2 |
| For products of prime factors, ignore inclusion of \(\times 1\) |