Denary to Hexadecimal Conversion exam questions

12 OCR GCSE Computer Science (J277) exam-style questions on Denary to Hexadecimal Conversion (1.2 Memory & Storage), 36 marks in all. Answer them on paper or print them, then open the mark schemes and example answers to see how each is marked.

Name
Class
Suggested time	45 minutes

1Convert2 marks

Computers store all data as binary.

Convert the denary number 42 into hexadecimal.

Show your working.

[2 marks]

Mark scheme

2 marks for the correct answer

No marks for working on its own (e.g. dividing by 16 (42 ÷ 16 = 2 remainder 10), or converting to 8-bit binary first (0010 1010)).

Guidance

Ignore case.

Example answers and how they were marked

Full marks2/2

42 ÷ 16 = 2 remainder 10

2 = 2, 10 = A

Answer: 2A

Why: The correct answer (2), found by dividing by 16 and using the remainder.

No marks0/2

42 ÷ 16 = 2 remainder 10

Answer: 210

Why: The working is right, but a digit over 9 is left in denary, so the answer is wrong (0).

No marks0/2

Why: No working (0), and the digits are the wrong way round (0).

2Convert2 marks

Computers store all data as binary.

Convert the denary number 173 into hexadecimal.

Show your working.

[2 marks]

Mark scheme

2 marks for the correct answer

No marks for working on its own (e.g. dividing by 16 (173 ÷ 16 = 10 remainder 13), or converting to 8-bit binary first (1010 1101)).

Guidance

Ignore case.

Example answers and how they were marked

Full marks2/2

173 ÷ 16 = 10 remainder 13

10 = A, 13 = D

Answer: AD

Why: The correct answer (2), found by dividing by 16 and using the remainder.

No marks0/2

173 ÷ 16 = 10 remainder 13

Answer: 1013

Why: The working is right, but a digit over 9 is left in denary, so the answer is wrong (0).

No marks0/2

Why: No working (0), and the digits are the wrong way round (0).

3Convert2 marks

Computers store all data as binary.

Convert the denary number 216 into hexadecimal.

Show your working.

[2 marks]

Mark scheme

2 marks for the correct answer

No marks for working on its own (e.g. dividing by 16 (216 ÷ 16 = 13 remainder 8), or converting to 8-bit binary first (1101 1000)).

Guidance

Ignore case.

Example answers and how they were marked

Full marks2/2

216 ÷ 16 = 13 remainder 8

13 = D, 8 = 8

Answer: D8

Why: The correct answer (2), found by dividing by 16 and using the remainder.

No marks0/2

216 ÷ 16 = 13 remainder 8

Answer: 138

Why: The working is right, but a digit over 9 is left in denary, so the answer is wrong (0).

No marks0/2

Why: No working (0), and the digits are the wrong way round (0).

4Convert2 marks

Computers represent data in binary form.

Convert the denary number 123 into hexadecimal.

Show your working.

[2 marks]

Mark scheme

2 marks for the correct answer

No marks for working on its own (e.g. dividing by 16 (123 ÷ 16 = 7 remainder 11), or converting to 8-bit binary first (0111 1011)).

Guidance

Ignore case.

Example answers and how they were marked

Full marks2/2

123 ÷ 16 = 7 remainder 11

7 = 7, 11 = B

Answer: 7B

Why: The correct answer (2), found by dividing by 16 and using the remainder.

No marks0/2

123 ÷ 16 = 7 remainder 11

Answer: 711

Why: The working is right, but a digit over 9 is left in denary, so the answer is wrong (0).

No marks0/2

Why: No working (0), and the digits are the wrong way round (0).

5Convert2 marks

Binary numbers can represent different forms of data.

Convert the denary number 164 into hexadecimal.

Show your working.

[2 marks]

Mark scheme

2 marks for the correct answer

No marks for working on its own (e.g. dividing by 16 (164 ÷ 16 = 10 remainder 4), or converting to 8-bit binary first (1010 0100)).

Guidance

Ignore case.

Example answers and how they were marked

Full marks2/2

164 ÷ 16 = 10 remainder 4

10 = A, 4 = 4

Answer: A4

Why: The correct answer (2), found by dividing by 16 and using the remainder.

No marks0/2

164 ÷ 16 = 10 remainder 4

Answer: 104

Why: The working is right, but a digit over 9 is left in denary, so the answer is wrong (0).

No marks0/2

Why: No working (0), and the digits are the wrong way round (0).

6Convert2 marks

Computers store all data as binary.

Convert the denary number 170 into hexadecimal.

Show your working.

[2 marks]

Mark scheme

2 marks for the correct answer

No marks for working on its own (e.g. dividing by 16 (170 ÷ 16 = 10 remainder 10), or converting to 8-bit binary first (1010 1010)).

Guidance

Ignore case.

Example answers and how they were marked

Full marks2/2

170 ÷ 16 = 10 remainder 10

10 = A, 10 = A

Answer: AA

Why: The correct answer (2), found by dividing by 16 and using the remainder.

No marks0/2

170 ÷ 16 = 10 remainder 10

Answer: 1010

Why: The working is right, but a digit over 9 is left in denary, so the answer is wrong (0).

No marks0/2

Why: No working (0), and the digits are the wrong way round (0).

7Convert4 marks

Computers represent data in binary form.

Complete the table by writing the missing denary, 8-bit binary or hexadecimal values.

[4 marks]

Denary	8-bit binary	Hexadecimal
94		5E
	10101101	AD
	11011001	D9
211	11010011

Mark scheme

1 mark for each completed box

Denary | 8-bit binary | Hexadecimal

94 | 01011110 | 5E

173 | 10101101 | AD

217 | 11011001 | D9

211 | 11010011 | D3

Guidance

Correct answers only – binary must be 8 bits.

Ignore case in hex.

Example answers and how they were marked

Full marks4/4

01011110

173

217

Why: Every missing value is correct, and the binary is 8 bits (4).

Some marks2/4

1011110

173

217

133

Why: Rows 2 and 3 are correct (2); row 1 (binary) leaves off the leading 0s, so it is not 8 bits (0) and row 4 (hexadecimal) has a digit over 9 written in denary (0).

No marks0/4

1011110

181

155

133

Why: None of the values is right: row 1 (binary) leaves off the leading 0s, so it is not 8 bits (0); row 2 (denary) reads the place values from the wrong end (0); row 3 (denary) reads the place values from the wrong end (0); row 4 (hexadecimal) has a digit over 9 written in denary (0).

8Convert4 marks

Computers store all data as binary.

Complete the table by writing the missing denary, 8-bit binary or hexadecimal values.

[4 marks]

Denary	8-bit binary	Hexadecimal
41		29
196		C4
	10010101	95
95	01011111

Mark scheme

1 mark for each completed box

Denary | 8-bit binary | Hexadecimal

41 | 00101001 | 29

196 | 11000100 | C4

149 | 10010101 | 95

95 | 01011111 | 5F

Guidance

Correct answers only – binary must be 8 bits.

Ignore case in hex.

Example answers and how they were marked

Full marks4/4

00101001

11000100

149

Why: Every missing value is correct, and the binary is 8 bits (4).

Some marks2/4

101001

11000100

149

515

Why: Rows 2 and 3 are correct (2); row 1 (binary) leaves off the leading 0s, so it is not 8 bits (0) and row 4 (hexadecimal) has a digit over 9 written in denary (0).

No marks0/4

101001

00100011

169

515

Why: None of the values is right: row 1 (binary) leaves off the leading 0s, so it is not 8 bits (0); row 2 (binary) is back to front (0); row 3 (denary) reads the place values from the wrong end (0); row 4 (hexadecimal) has a digit over 9 written in denary (0).

9Convert4 marks

Computers represent data in binary form.

Each row in the table contains a number written as a denary value, an 8-bit binary value and a 2-digit hexadecimal value. Some values are missing.

Complete the table by writing in the missing value for each number.

[4 marks]

Denary	8-bit binary	Hexadecimal
13	00001101
235		EB
179	10110011
	11011010	DA

Mark scheme

1 mark for each completed box

Denary | 8-bit binary | Hexadecimal

13 | 00001101 | 0D

235 | 11101011 | EB

179 | 10110011 | B3

218 | 11011010 | DA

Guidance

Correct answers only – binary must be 8 bits.

Ignore case in hex.

Example answers and how they were marked

Full marks4/4

11101011

218

Why: Every missing value is correct, and the binary is 8 bits (4).

Some marks2/4

013

11101011

Why: Rows 2 and 3 are correct (2); row 1 (hexadecimal) has a digit over 9 written in denary (0) and row 4 (denary) reads the place values from the wrong end (0).

No marks0/4

013

11010111

113

Why: None of the values is right: row 1 (hexadecimal) has a digit over 9 written in denary (0); row 2 (binary) is back to front (0); row 3 (hexadecimal) has a digit over 9 written in denary (0); row 4 (denary) reads the place values from the wrong end (0).

10Convert4 marks

Binary numbers can represent different forms of data.

Each row in the table contains a number written as a denary value, an 8-bit binary value and a 2-digit hexadecimal value. Some values are missing.

Complete the table by writing in the missing value for each number.

[4 marks]

Denary	8-bit binary	Hexadecimal
	01101100	6C
176		B0
173		AD
123	01111011

Mark scheme

1 mark for each completed box

Denary | 8-bit binary | Hexadecimal

108 | 01101100 | 6C

176 | 10110000 | B0

173 | 10101101 | AD

123 | 01111011 | 7B

Guidance

Correct answers only – binary must be 8 bits.

Ignore case in hex.

Example answers and how they were marked

Full marks4/4

108

10110000

10101101

Why: Every missing value is correct, and the binary is 8 bits (4).

Some marks2/4

10110000

10101101

711

Why: Rows 2 and 3 are correct (2); row 1 (denary) reads the place values from the wrong end (0) and row 4 (hexadecimal) has a digit over 9 written in denary (0).

No marks0/4

00001101

10110101

711

Why: None of the values is right: row 1 (denary) reads the place values from the wrong end (0); row 2 (binary) is back to front (0); row 3 (binary) is back to front (0); row 4 (hexadecimal) has a digit over 9 written in denary (0).

11Convert4 marks

Computers store all data as binary.

Each row in the table contains a number written as a denary value, an 8-bit binary value and a 2-digit hexadecimal value. Some values are missing.

Complete the table by writing in the missing value for each number.

[4 marks]

Denary	8-bit binary	Hexadecimal
	00101001	29
226	11100010
31		1F
205		CD

Mark scheme

1 mark for each completed box

Denary | 8-bit binary | Hexadecimal

41 | 00101001 | 29

226 | 11100010 | E2

31 | 00011111 | 1F

205 | 11001101 | CD

Guidance

Correct answers only – binary must be 8 bits.

Ignore case in hex.

Example answers and how they were marked

Full marks4/4

00011111

11001101

Why: Every missing value is correct, and the binary is 8 bits (4).

Some marks2/4

148

00011111

10110011

Why: Rows 2 and 3 are correct (2); row 1 (denary) reads the place values from the wrong end (0) and row 4 (binary) is back to front (0).

No marks0/4

148

142

11111

10110011

Why: None of the values is right: row 1 (denary) reads the place values from the wrong end (0); row 2 (hexadecimal) has a digit over 9 written in denary (0); row 3 (binary) leaves off the leading 0s, so it is not 8 bits (0); row 4 (binary) is back to front (0).

12Convert4 marks

Computers represent data in binary form.

Complete the table by writing the missing denary, 8-bit binary or hexadecimal values.

[4 marks]

Denary	8-bit binary	Hexadecimal
	11100011	E3
168	10101000
31	00011111
196		C4

Mark scheme

1 mark for each completed box

Denary | 8-bit binary | Hexadecimal

227 | 11100011 | E3

168 | 10101000 | A8

31 | 00011111 | 1F

196 | 11000100 | C4

Guidance

Correct answers only – binary must be 8 bits.

Ignore case in hex.

Example answers and how they were marked

Full marks4/4

227

11000100

Why: Every missing value is correct, and the binary is 8 bits (4).

Some marks2/4

199

00100011

Why: Rows 2 and 3 are correct (2); row 1 (denary) reads the place values from the wrong end (0) and row 4 (binary) is back to front (0).

No marks0/4

199

108

115

00100011

Why: None of the values is right: row 1 (denary) reads the place values from the wrong end (0); row 2 (hexadecimal) has a digit over 9 written in denary (0); row 3 (hexadecimal) has a digit over 9 written in denary (0); row 4 (binary) is back to front (0).

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