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