Factors & Multiples — Chapter Test | Class 5 IMO

Q1

Which is the odd one out (three are prime numbers)?

15 = 3 × 5 is composite; the others are prime.

Q2

Which is the prime factorization of 12?

12 = 2 × 2 × 3, all primes.

Q3

Which number is divisible by 9?

Digit sum of 108 is 1 + 0 + 8 = 9, divisible by 9.

Q4

The HCF of two numbers is the product of their ___ prime factors.

HCF uses the common prime factors.

Q5

What is the prime factorization of 24?

24 = 2 × 2 × 2 × 3.

Q6

What is the HCF of 12 and 18?

Common primes 2 and 3 give HCF = 6.

Q7

What is the LCM of 6 and 8?

6 = 2 × 3 and 8 = 2³; LCM = 2³ × 3 = 24.

Q8

Is 156 divisible by 4?

Last two digits 56 ÷ 4 = 14, so yes.

Q9

Is 99 divisible by 11?

99 = 9 × 11, so yes.

Q10

Two ropes of 12 m and 16 m are cut into equal pieces of the greatest length. What is that length?

Greatest length = HCF of 12 and 16 = 4 m.

Q11

Two lights blink every 6 seconds and 8 seconds. After how many seconds do they blink together?

They blink together at the LCM of 6 and 8, which is 24 seconds.

Q12

36 apples and 24 oranges are packed into boxes with equal numbers of each, using the largest box size. How many fruits of each go in a box?

Largest equal box size = HCF of 36 and 24 = 12.

Q13

What is the smallest number divisible by 4, 6 and 8?

LCM of 4, 6 and 8 is 24.

Q14

What is the prime factorization of 60?

60 = 2 × 2 × 3 × 5, all primes.