Lemmara logoLemmaraWorked solution

4MA1/1F Jan 2020, Question 15: HCF and LCM

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1F (Foundation) · Calculator · 4 marks

اقرأ هذا الحل مشروحاً بالعربي ←

The question, in short

Find the highest common factor of 28 and 70, then the lowest common multiple of 28 and 105.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 2 marks

Find the HCF of 28 and 70.

  1. 128 = 2 × 2 × 7
  2. 270 = 2 × 5 × 7
  3. 3common prime factors: 2 and 7
  4. 42 × 7 = 14

Answer14

Part (b) · 2 marks

Find the LCM of 28 and 105.

  1. 128 = 2 × 2 × 7
  2. 2105 = 3 × 5 × 7
  3. 3LCM = 2 × 2 × 3 × 5 × 7
  4. 44 × 3 = 12
  5. 512 × 5 = 60
  6. 660 × 7 = 420

Answer420

Stuck on a step? Read the free lesson: HCF and LCM

Practise more hcf and lcm questions

Real 4MA1 past-paper questions, marked on your working like the exam, with a worked solution for every part.

Practise free on Lemmara

More past-paper questions on hcf and lcm

Also searched as: 4MA1 1F January 2020 · 4MA1/1F · 4ma1 jan20 1f · question 15.
Lemmara is an independent study tool, not affiliated with or endorsed by Pearson Edexcel. The worked solutions are Lemmara’s own.