Higher January 2022 Paper 2 Q7
7 Find the lowest common multiple (LCM) of 28, 42 and 63
Show your working clearly.
(3)
| Scheme | Marks |
|---|---|
| \(2 \times 2 \times 7\) or \(2 \times 3 \times 7\) or \(3^2 \times 7\) oe condone 1’s in factor tree or showing at least 5 correct multiples across at least 2 lists (excluding 28, 42, 63) (28) 56, 84, 112, 140, 168, 196, 224, 252 (42) 84, 126, 168, 210, 252 (63) 126, 189, 252 | M1 |
| \(2 \times 2 \times 7\) and \(2 \times 3 \times 7\) and \(3 \times 3 \times 7\) or showing at least 9 correct multiples across all 3 lists (excluding 28, 42, 63) | M1 |
| Working required Answer: 252 | A1 |
| (3) | |
| (3 marks) |
Notes
M1: accept prime factors seen in factor tree or correct position in Venn diagram for at least one of the numbers given.
M1: accept prime factors seen in factor tree or correct position in Venn diagram for all 3 of the numbers given.
A1: or \(2^2 \times 3^2 \times 7\) oe Dep on M1
ALTERNATIVE
| Scheme | Marks | ||||||||||||||||||||||||
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| M1 | ||||||||||||||||||||||||
or
| M1 | ||||||||||||||||||||||||
| Working required Answer: 252 | A1 |
Notes
M1: For one correct row in table
eg division by 7 gives 4, 6, 9
M1: Fully correct table – need only go as far as top table – we want to see prime factors along the side or prime factors along the sides and bottom (condone 1’s)
A1: or \(2^2 \times 3^2 \times 7\) oe Dep on M1