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