Mathematics for IGCSE & O level - Number (Section 1)
1
Which of the following is a composite number?
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(D)
12
2
Identify a pair of numbers where their HCF is 1.
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(C)
7 and 10
3
What is the reciprocal of 1/5?
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(B)
5
4
What is the simplified fraction for 0.5?
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(A)
1/2
5
What are the prime factors of 42?
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(A)
2, 3, 7
6
Which of the following is a prime number?
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(C)
23
7
Which statement is true about the reciprocal of a number?
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(B)
The reciprocal of a whole number is always a fraction.
8
Which of the following is the same as 0.666...
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(B)
2/3
9
Which of the following statements are true regarding the highest common factor (HCF)?
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A
B
D
10
Which of the following are rational numbers?
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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?
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(B)
12 mm
12
Which of these is a correct description of a rational number?
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(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?
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(C)
3
14
What is the HCF of 12 and 15?
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(B)
3
15
Which of the following is equivalent to 0. 25?
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(C)
1/4
16
Which of the following is NOT a rational number?
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(C)
√2
17
What is the reciprocal of -2?
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(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?
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(C)
6
19
What are the prime factors of 28?
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(B)
2, 2, 7
20
What are the prime factors of 18?
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(B)
2, 3, 3
21
What is the LCM of 8 and 10?
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(B)
40
22
What is the next number in the sequence: 2, 3, 5, 7, ...?
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(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?
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(C)
21
24
What type of number is √16?
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(B)
Integer
25
Which statement about prime numbers is correct?
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(C)
There are infinitely many prime numbers.
26
Which of the following numbers is NOT a factor of 36?
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(D)
11
27
What is 5^2 - 3^2?
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(B)
16
28
What is the LCM of 15 and 20?
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(C)
60
29
What are the first four prime numbers?
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(B)
2, 3, 5, 7
30
What is the lowest common multiple (LCM) of 4 and 6?
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(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?
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(A)
10
32
What is the prime factorization of 50?
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(B)
2 x 5^2
33
What is the square root of 144?
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(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?
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(A)
10:00 am
35
What is the value of √81?
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(B)
9
36
What is the HCF of 16 and 24?
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(C)
8
37
What is the highest common factor (HCF) of 24 and 36?
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(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?
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(C)
9
39
What is the product of the prime factors of 30?
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(B)
30
40
What is the prime factorization of 72?
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(C)
2^3 x 3^2
41
Which number has the prime factors 2, 3, and 5?
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(C)
30
42
Which of the following is an example of a recurring decimal?
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(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?
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(B)
10:04 PM
44
Which of the following sets of numbers are all natural numbers?
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(B)
1, 2, 3, 4
45
Which of the following is NOT a property of prime numbers?
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(C)
They are all odd numbers.
46
What is the reciprocal of 2/3?
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(C)
3/2
47
What is the name for a number that cannot be written as a fraction?
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(C)
Irrational number
48
Which of the following numbers is NOT a natural number?
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(A)
0
49
Which set of numbers are all integers?
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(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?
