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3 questions · 5 marks
Computer systems manipulate bit patterns.
Convert the hexadecimal number D5 to denary.
Award one mark for:
213
Why: 13 × 16 + 5 = 213 (1).
93
Why: Takes the right-hand digit as the 16s, so the value is wrong.
18
Why: Adds the two digits instead of multiplying the first by 16.
Binary, denary and hexadecimal patterns represent numbers.
Convert the hexadecimal number B7 to 8-bit binary.
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
1011 0111
Why: Each digit is 4 bits: B = 1011, 7 = 0111 (2).
1011 1000
Why: Converts 7 as if it were the next digit up. The first nibble is correct (1); the second is not.
0111 1011
Why: The nibbles are in the wrong order. Neither nibble is correct.
Computers manipulate binary patterns.
Convert the hexadecimal number 1F to 8-bit binary.
Award one mark for each correct nibble in the correct order:
0 marks if the response is not 8-bit binary.
0001 1111
Why: Each digit is 4 bits: 1 = 0001, F = 1111 (2).
0001 0000
Why: Converts F as if it were the next digit up. The first nibble is correct (1); the second is not.
1111 0001
Why: The nibbles are in the wrong order. Neither nibble is correct.
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