IGCSE Computer Science – Chapter 1: Number Systems

How many digits are used in the hexadecimal number system (Base 16)?

• 10

• 12

• 14

• 16

Answer explanation

The hexadecimal number system, or Base 16, uses 16 distinct symbols: 0-9 for values zero to nine and A-F for values ten to fifteen. Therefore, the correct answer is 16.

What is the binary representation of the hexadecimal digit 0?

• The binary representation of the hexadecimal digit 0 is 0000.

• The binary representation of the hexadecimal digit 0 is 0001.

• The binary representation of the hexadecimal digit 0 is 0010.

• The binary representation of the hexadecimal digit 0 is 0011.

Answer explanation

The hexadecimal digit 0 corresponds to the binary value 0000. Each hex digit represents a 4-bit binary number, and 0 in hex is 0 in binary.

What is the binary representation of the hexadecimal digit 4?

• 0100

• 0001

• 1000

• 0010

Answer explanation

The hexadecimal digit 4 is represented in binary as 0100. Each hex digit corresponds to a 4-bit binary number, and 4 in decimal is 4 in binary, which is 0100.

What is the binary representation of the hexadecimal digit 5?

• 0101

• 1100

• 1010

• 0110

Answer explanation

The hexadecimal digit 5 is represented in binary as 0101. Each hex digit corresponds to a 4-bit binary number, and 5 in decimal is 0101 in binary.

What is the binary representation of the hexadecimal digit 9?

• 1001

• 1010

• 1100

• 1111

Answer explanation

The hexadecimal digit 9 is represented in binary as 1001. Each hex digit corresponds to a 4-bit binary number, and 9 in decimal is 1001 in binary.

What is the binary representation of the hexadecimal digit A?

• The binary representation of the hexadecimal digit A is 1010.

• The binary representation of the hexadecimal digit A is 1100.

• The binary representation of the hexadecimal digit A is 1001.

• The binary representation of the hexadecimal digit A is 1110.

Answer explanation

The hexadecimal digit A corresponds to the decimal value 10. In binary, 10 is represented as 1010. Therefore, the correct answer is that the binary representation of the hexadecimal digit A is 1010.

What digits are used in the octal number system?

• 0-7

• 0-9

• 0-8

• 1-8

Answer explanation

The octal number system uses digits from 0 to 7. This means it has a base of 8, allowing for eight unique digits. Therefore, the correct answer is 0-7.

Convert 1101 0111₂ (Binary) to Hexadecimal (Base 16). What is the hexadecimal equivalent?

• A. D7

• B. E7

• C. F7

• D. C7

Answer explanation

To convert 1101 0111₂ to hexadecimal, group the binary digits into pairs from the right: 11 01 01 11. This corresponds to D (13) and 7 (7) in hex. Thus, the hexadecimal equivalent is D7, making A the correct choice.

Convert the hexadecimal digit 4 to binary.

• 0100

• 1000

• 0010

• 0001

Answer explanation

The hexadecimal digit 4 converts to binary as follows: 4 in decimal is 4, which is represented in binary as 0100. Therefore, the correct answer is 0100.

Convert the hexadecimal digit 6 to binary.

• 0110

• 0101

• 1001

• 0011

Answer explanation

The hexadecimal digit 6 converts to binary as 0110. Each hex digit corresponds to a 4-bit binary number, and 6 in decimal is represented as 0110 in binary.