10 questions · Form 1 Mathematics Bab 2: Factors and Multiples
Express 72 as a product of its prime factors.
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. Express 72 as a product of its prime factors.
Answer: A
72 = 8 × 9 = (2 × 2 × 2) × (3 × 3) = 23 × 32.
2. Find the Lowest Common Multiple (LCM) of 6 and 8.
Answer: A
Multiples of 6: 6, 12, 18, 24... Multiples of 8: 8, 16, 24... The smallest common multiple is 24.
3. Find the Highest Common Factor (HCF) of 16, 24, and 32.
Answer: A
Using repeated division: 16 ÷ 8 = 2, 24 ÷ 8 = 3, 32 ÷ 8 = 4. Since 2, 3, 4 share no common factors, HCF = 8.
4. How many factors does the number 20 have in total?
Answer: A
Factors of 20 are 1, 2, 4, 5, 10, and 20 (6 factors in total).
5. The difference between the LCM and HCF of 15 and 20 is...
Answer: A
HCF(15, 20) = 5. LCM(15, 20) = 60. Difference = 60 - 5 = 55.
6. Which of the following is a prime number?
Answer: A
29 has only two factors (1 and 29), making it a prime number.
7. What is the sum of all prime factors of 42?
Answer: A
Prime factors of 42 = 2, 3, 7. Sum = 2 + 3 + 7 = 12.
8. Which of the following is a common factor of 18 and 24?
Answer: A
Factors of 18: 1, 2, 3, 6, 9, 18. Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24. Shared factors are 1, 2, 3, and 6.
9. If the HCF of two numbers is 6 and their LCM is 36, and one of the numbers is 12, what is the other number?
Answer: A
Formula: Number A × Number B = HCF × LCM. 12 × B = 6 × 36 = 216. B = 216 ÷ 12 = 18.
10. What are all the prime factors of 30?
Answer: A
30 = 2 × 3 × 5. Note that 1 is not a prime number.