Foundation June 2018 Paper 1 Q13
13
(a) Show that the highest common factor (HCF) of 18 and 63 is 9. [2]
(b) Find the lowest common multiple (LCM) of 18 and 63. [2]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| Showing that 9 is a common factor of 18 and 63 | 1 | 9 appearing in both lists of factors. 9 \(\times\) 2 = 18 9 \(\times\) 7 = 63 or both 18 and 63 can be divided by 9 Venn diagram with 3 and 3 in the centre 18 = 2 \(\times\) 3 \(\times\) 3 and 63 = 3 \(\times\) 3 \(\times\) 7 oe Accept factor trees with 2,3 and 3 and 3,3,7 at the ends | |
| Showing there is no greater common factor | 1 | 9 must be clearly identified as the highest factor it may be ringed or underlined. Do not accept \(3^2\) for 9. If listing factors we need to see a complete list for both 18 and 63 in order to award 2 marks | |
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 126 | 2 | M1 for listing at least 4 multiples of 18 or 2 x 3 x 3 x 7 or any common multiple of 18 and 63 | could be from Venn diagram approach |