IMO Practice Test — Factors & Multiples
6 Questions • 12 min • Olympiad level
12:00
Question 1 of 6
hard
Which number is both prime and a multiple of 5?
5
10
15
25
Explanation: 5 is prime; the other multiples of 5 here are composite.
Question 2 of 6
hard
I am less than 30, a multiple of 4, and also a multiple of 6. I am…
12
16
18
20
Explanation: 12 and 24 are in both tables; the option here is 12.
Question 3 of 6
hard
The sum of the first three prime numbers is…
9
10
11
6
Explanation: 2 + 3 + 5 = 10.
Question 4 of 6
medium
The smallest common multiple of 5 and 6 is…
11
30
60
25
Explanation: No common factor, so 5 × 6 = 30.
Question 5 of 6
hard
Which number has exactly 3 factors?
6
8
9
10
Explanation: 9 has factors 1, 3, 9 (a prime squared has exactly 3 factors).
Question 6 of 6
hard
The smallest common multiple of 4, 6 and 8 is…
24
48
12
16
Explanation: 24 is divisible by 4, 6 and 8.