IMO Practice Test — Factors, Multiples, HCF & LCM
6 Questions • 25 min • Olympiad level
25:00
Question 1 of 6
medium
Which is a common multiple of 2 and 3?
6
8
9
10
Explanation: 6 is in both the 2- and 3-times tables.
Question 2 of 6
hard
The largest square tile that can exactly cover a 12 cm by 18 cm rectangle has side…
4 cm
6 cm
9 cm
3 cm
Explanation: The side is the HCF of 12 and 18 = 6 cm.
Question 3 of 6
medium
The HCF of two different prime numbers is always…
1
their product
the bigger one
0
Explanation: Different primes share only the factor 1.
Question 4 of 6
medium
How many factors does 24 have?
6
7
8
5
Explanation: 1, 2, 3, 4, 6, 8, 12, 24 → eight factors.
Question 5 of 6
medium
Which of these is NOT prime?
29
31
33
37
Explanation: 33 = 3 × 11, so it is composite.
Question 6 of 6
medium
How many prime numbers are there between 10 and 20?
3
4
5
2
Explanation: 11, 13, 17, 19 → four primes.