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