12 OCR GCSE Computer Science (J277) exam-style questions on Binary to Denary Conversion (1.2 Memory & Storage), 24 marks in all. Answer them on paper or print them, then open the mark schemes and example answers to see how each is marked.
Computers represent data in binary form.
Convert the 8-bit binary number 11110011 into denary.
Guidance
Correct answer only
243
Why: 128 + 64 + 32 + 16 + 2 + 1 = 243 (1).
207
Why: Reads the place values from the wrong end, so the value is wrong (0).
6
Why: Counts the 1s instead of adding their place values (0).
Computers represent data in binary form.
Convert the 8-bit binary number 11000100 into denary.
Guidance
Correct answer only
196
Why: 128 + 64 + 4 = 196 (1).
35
Why: Reads the place values from the wrong end, so the value is wrong (0).
3
Why: Counts the 1s instead of adding their place values (0).
Computers represent data in binary form.
Convert the 8-bit binary number 01001011 into denary.
Guidance
Correct answer only
75
Why: 64 + 8 + 2 + 1 = 75 (1).
210
Why: Reads the place values from the wrong end, so the value is wrong (0).
4
Why: Counts the 1s instead of adding their place values (0).
Binary numbers can represent different forms of data.
Convert the 8-bit binary number 00111011 into denary.
Guidance
Correct answer only
59
Why: 32 + 16 + 8 + 2 + 1 = 59 (1).
220
Why: Reads the place values from the wrong end, so the value is wrong (0).
5
Why: Counts the 1s instead of adding their place values (0).
Computers represent data in binary form.
Convert the 8-bit binary number 00011001 into denary.
Guidance
Correct answer only
25
Why: 16 + 8 + 1 = 25 (1).
152
Why: Reads the place values from the wrong end, so the value is wrong (0).
3
Why: Counts the 1s instead of adding their place values (0).
Computers represent data in binary form.
Convert the 8-bit binary number 01000101 into denary.
Guidance
Correct answer only
69
Why: 64 + 4 + 1 = 69 (1).
162
Why: Reads the place values from the wrong end, so the value is wrong (0).
3
Why: Counts the 1s instead of adding their place values (0).
Computers represent data in binary form.
The following table has either the binary or denary value of 3 numbers.
Complete the table by converting each 8-bit binary number into denary and the denary number into 8-bit binary.
| 8-bit Binary | Denary |
|---|---|
| 10010101 | |
| 126 | |
| 00001110 |
1 mark each
8-bit Binary | Denary
10010101 | 149
01111110 | 126
00001110 | 14
Guidance
Binary must be 8 bits
149
01111110
14
Why: All three conversions are correct (3).
149
1111110
14
Why: The binary to denary conversions are right (2), but row 2 (binary) leaves off the leading 0s, so it is not 8 bits (0).
169
1111110
112
Why: None is right: row 1 (denary) reads the place values from the wrong end; row 2 (binary) leaves off the leading 0s, so it is not 8 bits; row 3 (denary) reads the place values from the wrong end (0).
Computers store all data as binary.
The following table has either the binary or denary value of 3 numbers.
Complete the table by converting each 8-bit binary number into denary and the denary number into 8-bit binary.
| 8-bit Binary | Denary |
|---|---|
| 01111101 | |
| 159 | |
| 00001010 |
1 mark each
8-bit Binary | Denary
01111101 | 125
10011111 | 159
00001010 | 10
Guidance
Binary must be 8 bits
125
10011111
10
Why: All three conversions are correct (3).
125
11111001
10
Why: The binary to denary conversions are right (2), but row 2 (binary) is back to front (0).
190
11111001
80
Why: None is right: row 1 (denary) reads the place values from the wrong end; row 2 (binary) is back to front; row 3 (denary) reads the place values from the wrong end (0).
Computers represent data in binary form.
The following table has either the binary or denary value of 3 numbers.
Complete the table by converting each 8-bit binary number into denary and the denary number into 8-bit binary.
| 8-bit Binary | Denary |
|---|---|
| 11011101 | |
| 24 | |
| 11100001 |
1 mark each
8-bit Binary | Denary
11011101 | 221
00011000 | 24
11100001 | 225
Guidance
Binary must be 8 bits
221
00011000
225
Why: All three conversions are correct (3).
221
11000
225
Why: The binary to denary conversions are right (2), but row 2 (binary) leaves off the leading 0s, so it is not 8 bits (0).
187
11000
135
Why: None is right: row 1 (denary) reads the place values from the wrong end; row 2 (binary) leaves off the leading 0s, so it is not 8 bits; row 3 (denary) reads the place values from the wrong end (0).
Binary numbers can represent different forms of data.
The following table has either the binary or denary value of 3 numbers.
Complete the table by converting each 8-bit binary number into denary and the denary number into 8-bit binary.
| 8-bit Binary | Denary |
|---|---|
| 202 | |
| 01001100 | |
| 01100111 |
1 mark each
8-bit Binary | Denary
11001010 | 202
01001100 | 76
01100111 | 103
Guidance
Binary must be 8 bits
11001010
76
103
Why: All three conversions are correct (3).
01010011
76
103
Why: The binary to denary conversions are right (2), but row 1 (binary) is back to front (0).
01010011
50
230
Why: None is right: row 1 (binary) is back to front; row 2 (denary) reads the place values from the wrong end; row 3 (denary) reads the place values from the wrong end (0).
Binary numbers can represent different forms of data.
The following table has either the binary or denary value of 3 numbers.
Complete the table by converting each 8-bit binary number into denary and the denary number into 8-bit binary.
| 8-bit Binary | Denary |
|---|---|
| 00111101 | |
| 147 | |
| 10001000 |
1 mark each
8-bit Binary | Denary
00111101 | 61
10010011 | 147
10001000 | 136
Guidance
Binary must be 8 bits
61
10010011
136
Why: All three conversions are correct (3).
61
11001001
136
Why: The binary to denary conversions are right (2), but row 2 (binary) is back to front (0).
188
11001001
17
Why: None is right: row 1 (denary) reads the place values from the wrong end; row 2 (binary) is back to front; row 3 (denary) reads the place values from the wrong end (0).
Binary numbers can represent different forms of data.
The following table has either the binary or denary value of 3 numbers.
Complete the table by converting each 8-bit binary number into denary and the denary number into 8-bit binary.
| 8-bit Binary | Denary |
|---|---|
| 01011001 | |
| 00010000 | |
| 65 |
1 mark each
8-bit Binary | Denary
01011001 | 89
00010000 | 16
01000001 | 65
Guidance
Binary must be 8 bits
89
16
01000001
Why: All three conversions are correct (3).
89
16
1000001
Why: The binary to denary conversions are right (2), but row 3 (binary) leaves off the leading 0s, so it is not 8 bits (0).
154
8
1000001
Why: None is right: row 1 (denary) reads the place values from the wrong end; row 2 (denary) reads the place values from the wrong end; row 3 (binary) leaves off the leading 0s, so it is not 8 bits (0).
Teachers: print these as a worksheet with the mark schemes at the end, and sign your school up to set your classes activities on Binary to Denary Conversion.
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