Mathematics for IGCSE & O level - Number (Section 1)
1
Which of the following is a composite number?
Answer
(D)
12
2
Identify a pair of numbers where their HCF is 1.
Answer
(C)
7 and 10
3
What is the reciprocal of 1/5?
Answer
(B)
5
4
What is the simplified fraction for 0.5?
Answer
(A)
1/2
5
What are the prime factors of 42?
Answer
(A)
2, 3, 7
6
Which of the following is a prime number?
Answer
(C)
23
7
Which statement is true about the reciprocal of a number?
Answer
(B)
The reciprocal of a whole number is always a fraction.
8
Which of the following is the same as 0.666...
Answer
(B)
2/3
9
Which of the following statements are true regarding the highest common factor (HCF)?
Answer
A
B
D
10
Which of the following are rational numbers?
Answer
A
C
D
11
A rectangle has dimensions 240 mm by 204 mm. What is the largest possible side length for identical squares that can cover the rectangle completely?
Answer
(B)
12 mm
12
Which of these is a correct description of a rational number?
Answer
(B)
A number that can be expressed as a terminating or recurring decimal.
13
Which of the following is a common factor of 18 and 24?
Answer
(C)
3
14
What is the HCF of 12 and 15?
Answer
(B)
3
15
Which of the following is equivalent to 0. 25?
Answer
(C)
1/4
16
Which of the following is NOT a rational number?
Answer
(C)
√2
17
What is the reciprocal of -2?
Answer
(B)
-1/2
18
The prime factorization of 120 is 2^3 x 3 x 5. Based on this, which of the following is a factor of 120?
Answer
(C)
6
19
What are the prime factors of 28?
Answer
(B)
2, 2, 7
20
What are the prime factors of 18?
Answer
(B)
2, 3, 3
21
What is the LCM of 8 and 10?
Answer
(B)
40
22
What is the next number in the sequence: 2, 3, 5, 7, ...?
Answer
(D)
11
23
The HCF of two numbers is 7, and the LCM is 42. If one of the numbers is 14, what is the other number?
Answer
(C)
21
24
What type of number is √16?
Answer
(B)
Integer
25
Which statement about prime numbers is correct?
Answer
(C)
There are infinitely many prime numbers.
26
Which of the following numbers is NOT a factor of 36?
Answer
(D)
11
27
What is 5^2 - 3^2?
Answer
(B)
16
28
What is the LCM of 15 and 20?
Answer
(C)
60
29
What are the first four prime numbers?
Answer
(B)
2, 3, 5, 7
30
What is the lowest common multiple (LCM) of 4 and 6?
Answer
(B)
12
31
The HCF of two numbers is 5. The LCM of the same two numbers is 60. If one of the numbers is 15, what is the other number?
Answer
(A)
10
32
What is the prime factorization of 50?
Answer
(B)
2 x 5^2
33
What is the square root of 144?
Answer
(B)
12
34
If a bus leaves a station every 40 minutes and a train leaves the same station every 45 minutes, at what time will they next leave the station together, assuming they both left the station at 7:00 am?
Answer
(A)
10:00 am
35
What is the value of √81?
Answer
(B)
9
36
What is the HCF of 16 and 24?
Answer
(C)
8
37
What is the highest common factor (HCF) of 24 and 36?
Answer
(B)
12
38
The HCF of two numbers is 3. The LCM of the same two numbers is 18. If one number is 6, what is the other number?
Answer
(C)
9
39
What is the product of the prime factors of 30?
Answer
(B)
30
40
What is the prime factorization of 72?
Answer
(C)
2^3 x 3^2
41
Which number has the prime factors 2, 3, and 5?
Answer
(C)
30
42
Which of the following is an example of a recurring decimal?
Answer
(B)
0.333...
43
Two lighthouses flash at intervals of 22 seconds and 16 seconds, respectively. If they flash together at 10:00 PM, when will they next flash together?
Answer
(B)
10:04 PM
44
Which of the following sets of numbers are all natural numbers?
Answer
(B)
1, 2, 3, 4
45
Which of the following is NOT a property of prime numbers?
Answer
(C)
They are all odd numbers.
46
What is the reciprocal of 2/3?
Answer
(C)
3/2
47
What is the name for a number that cannot be written as a fraction?
Answer
(C)
Irrational number
48
Which of the following numbers is NOT a natural number?
Answer
(A)
0
49
Which set of numbers are all integers?
Answer
(B)
-3, 0, 5, 9
50
If the LCM of two numbers is 36 and their HCF is 6, which of the following pairs could be the two numbers?
