IMO Number Theory

Question 1

Which of the following numbers is a prime number?

Accepted Answer

29

Answer

21

Answer

27

Answer

33

Question 2

What is the LCM of 4 and 6?

Accepted Answer

12

Answer

10

Answer

24

Answer

48

Question 3

What is the HCF (GCD) of 18 and 24?

Accepted Answer

6

Answer

3

Answer

4

Answer

9

Question 4

Which of the following is a composite number?

Accepted Answer

15

Answer

2

Answer

7

Answer

11

Question 5

What are the prime factors of 36?

Accepted Answer

2 and 3

Answer

3 and 4

Answer

2, 3, and 6

Answer

4 and 9

Question 6

Which of the following numbers is divisible by both 3 and 4?

Accepted Answer

24

Answer

18

Answer

20

Answer

30