Chapter 1 Practice Paper: Primes, HCF and LCM — question paper (print)

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QQ/S1MATH/CH1

Secondary 1 · Lower Secondary Mathematics (G2 / G3)

Chapter 1 Practice Paper

Primes, HCF and LCM

Duration: 40 minutes

Total: 30 marks

Name:

Class:

Date:

READ THESE INSTRUCTIONS FIRST

Write your name, class and register number in the spaces at the top of this page.
Answer all questions.
Section A: write the letter (A, B, C or D) of the correct answer in the brackets provided.
Section B: write your answers in the spaces provided.
Show all working. Marks may be awarded for correct working even if the final answer is wrong.
Give units with your answers where appropriate.
The number of marks is given in brackets [ ] at the end of each question or part question.

Original practice material written for the MOE Lower Secondary Mathematics syllabus. It is not an official MOE or school examination paper. Chapter 1.

For Examiner’s Use
Section A	/ 10
Section B	/ 20
Total	/ 30

Section A: Multiple-choice questions[10 marks]

Answer all questions. For each question, write the letter (A, B, C or D) of the correct answer in the brackets provided.

1
Which of the following numbers is a prime number?
1. A51
2. B59
3. C63
4. D81
( )
2
The number 1 is
1. Aa prime number
2. Ba composite number
3. Cneither prime nor composite
4. Dboth prime and composite
( )
3
The prime factorisation of 60, written in index notation, is
1. A2² × 3 × 5
2. B2 × 3 × 10
3. C6 × 10
4. D2 × 30
( )
4
The highest common factor of 18 and 24 is
1. A3
2. B4
3. C9
4. D6
( )
5
The lowest common multiple of 6 and 8 is
1. A2
2. B24
3. C48
4. D12
( )
6
Which expression shows 40 as a product of its prime factors in index notation?
1. A2 × 4 × 5
2. B2² × 10
3. C2³ × 5
4. D4 × 10
( )
7
Which of the following is a perfect square?
1. A18
2. B40
3. C68
4. D81
( )
8
The cube root of 64 is
1. A4
2. B6
3. C8
4. D16
( )
9
360 = 2³ × 3² × 5 and 84 = 2² × 3 × 7. The HCF of 360 and 84 is
1. A6
2. B12
3. C24
4. D36
( )
10
Two bells ring together at 09:00. One rings every 8 minutes and the other every 12 minutes. When do they next ring together?
1. A09:20
2. B09:36
3. C09:24
4. D09:48
( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided. Show your working clearly.

1
Use prime factorisation to answer this question.
1. (a)
  Write 84 as a product of its prime factors, giving your answer in index notation.
  [1]
2. (b)
  Write 126 as a product of its prime factors, giving your answer in index notation.
  [1]
3. (c)
  Hence find the highest common factor of 84 and 126.
  HCF =[1]
4. (d)
  Hence find the lowest common multiple of 84 and 126.
  LCM =[2]
2
This question is about squares, cubes and their roots.
1. (a)
  Write 216 as a product of prime factors, using index notation.
  [1]
2. (b)
  Using your answer to (a), explain how to find the cube root of 216 without a calculator, and state the value.
  [2]
3. (c)
  Given that 441 = 3² × 7², find the square root of 441 without a calculator.
  square root of 441 =[2]
3
A photographer has two ribbons, one 96 cm long and one 120 cm long. She cuts both ribbons into pieces of the same length, using the longest possible length so that no ribbon is left over.
1. (a)
  Find the greatest possible length of each piece. Explain your method.
  [3]
2. (b)
  How many pieces does she cut in total?
  total pieces =[2]
4
A ferry leaves Changi Point for Pulau Ubin every 15 minutes. A ferry for Pulau Tekong leaves every 20 minutes. At 08:45, ferries to both islands leave together.
1. (a)
  Show that the next time the two ferries leave together is 60 minutes later.
  [2]
2. (b)
  State the time at which the two ferries next leave together.
  time =[1]
3. (c)
  A student says the two ferries should leave together again after 30 minutes. Explain why 30 minutes cannot be correct.
  [2]

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