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Prime Factors, HCF & LCMEdexcel IGCSE Maths: Subtopic test

10 questions, 26 marks

Edexcel IGCSE Maths

Prime Factors, HCF & LCM

Total 26 marks

Name

Class

Date

  1. 1
    Two garden centres, Greenfield and Rosewood, are ordering matching sets of plant pots and trays. Greenfield orders 360 identical pots and Rosewood orders 252 identical pots.
    (a)
    Express 360 as a product of prime factors.
    [1 mark]
    • A23×32×52^3 \times 3^2 \times 5
    • B22×33×52^2 \times 3^3 \times 5
    • C23×3×522^3 \times 3 \times 5^2
    • D24×322^4 \times 3^2
    (b)
    Express 252 as a product of prime factors.
    [1 mark]
    • A22×3×722^2 \times 3 \times 7^2
    • B23×3×72^3 \times 3 \times 7
    • C2×33×72 \times 3^3 \times 7
    • D22×32×72^2 \times 3^2 \times 7
    (c)
    What is the highest common factor (HCF) of 360 and 252?
    [1 mark]
    • A1818
    • B3636
    • C1212
    • D7272

    Total for question 1: 3 marks

  2. 2
    Two lighthouses flash at regular intervals to warn passing ships. Lighthouse A flashes every 18 seconds and Lighthouse B flashes every 24 seconds. Both flash together at exactly 8:00pm.
    (a)
    Two lighthouses flash at regular intervals. Lighthouse A flashes every 18 seconds and Lighthouse B flashes every 24 seconds. Find the lowest common multiple (LCM) of 18 and 24.
    [2 marks]
    (b)
    Using your answer to part (a), find the next time after 8:00pm that both lighthouses flash together.
    [2 marks]

    Total for question 2: 4 marks

  3. 3
    A ribbon factory has two rolls of ribbon, one of length 84 metres and one of length 126 metres, and wants to cut both into equal-length pieces with none left over, then package the pieces into identical boxes.
    (a)
    Find the HCF of 84 and 126 using prime factorisation.
    [3 marks]
    (b)
    Using the piece length found in part (a), calculate the total number of pieces of ribbon produced from both rolls combined.
    [3 marks]

    Total for question 3: 6 marks

  4. 4
    A school is organising three coach trips departing from the same car park at 9:00am. Coach P returns every 30 minutes, Coach Q every 45 minutes and Coach R every 60 minutes. The school also wants to split 90 students into equal groups matching a factor of the LCM.
    (a)
    A school is organising three coach trips that depart from the same car park. Coach P returns every 30 minutes, Coach Q returns every 45 minutes and Coach R returns every 60 minutes, all starting together at 9:00am. Find the LCM of 30, 45 and 60 by writing each number as a product of its prime factors.
    [4 marks]
    (b)
    At what time will all three coaches next be back at the car park together?
    [4 marks]
    (c)
    The school wants to divide the students from three year groups, of sizes 90, 108 and 126, into the largest possible number of equal groups so that each group contains a whole number of students from each of the three year groups. Find the HCF of 90, 108 and 126 using prime factorisation, and state the number of groups formed.
    [5 marks]

    Total for question 4: 13 marks

End of questions