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Factors & Multiples — Chapter Test

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Q1
Which is the odd one out (three are prime numbers)?
9 = 3 × 3 is composite; the others are prime.
Q2
Continue the multiples of 5: 5, 10, 15, ___ ?
Add 5: 15 + 5 = 20.
Q3
Which number is a factor of 20?
5 divides 20 exactly (5 × 4 = 20).
Q4
Which number is divisible by 3?
Digit sum of 27 is 2 + 7 = 9, which is divisible by 3.
Q5
How many factors does 10 have?
The factors of 10 are 1, 2, 5 and 10 — that is 4.
Q6
Which of these is a composite number?
9 has factors 1, 3 and 9, so it is composite.
Q7
What is the 4th multiple of 8?
8 × 4 = 32.
Q8
What is the HCF of 12 and 16?
Common factors are 1, 2, 4; the highest is 4.
Q9
What is the LCM of 4 and 6?
The smallest common multiple of 4 and 6 is 12.
Q10
24 chocolates are packed in equal groups. Which group size will NOT work (leaves some over)?
5 is not a factor of 24, so groups of 5 leave some over.
Q11
Two bells ring every 4 minutes and 6 minutes. After how many minutes do they ring together?
They ring together at the LCM of 4 and 6, which is 12 minutes.
Q12
Two ribbons of 12 m and 18 m are cut into equal pieces of the greatest possible length. What is that length?
The greatest length is the HCF of 12 and 18, which is 6 m.
Q13
What is the smallest number that is divisible by both 3 and 4?
The LCM of 3 and 4 is 12.
Q14
Which number between 20 and 30 is a prime number?
23 has only the factors 1 and 23, so it is prime.
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