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0580/22 May/Jun 2026, Question 9: Prime factors, LCM and HCF

Cambridge IGCSE Mathematics 0580 · Paper 22 (Extended) · Non-calculator · 6 marks

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The question, in short

Work with prime factors of 63 and 42 to find an LCM, and find the HCF of two algebraic terms.

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

Part (a) · 2 marks

Write 63 as a product of prime factors.

  1. 163 = 3 × 21
  2. 221 = 3 × 7
  3. 363 = 3² × 7

Answer3 × 3 × 7 or 3² × 7

Part (b) · 2 marks

Find the LCM of 63 and 42.

  1. 163 = 3² × 7, 42 = 2 × 3 × 7
  2. 2LCM = 2 × 3² × 7
  3. 3= 126

Answer126

Part (c) · 2 marks

Find the HCF of 63a⁵c² and 42a²c⁵.

  1. 1HCF of 63 and 42 is 21
  2. 2Lowest power of a is a², lowest power of c is c²
  3. 3HCF = 21a²c²

Answer21a²c²

Stuck on a step? Read the free lesson: Prime Factorization

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