Build a practice paper from 693 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.
3 questions · 4 marks
Binary, denary and hexadecimal patterns represent numbers.
Convert the binary pattern 1110 1100 to denary.
Award one mark for:
236
Why: Correct: 128 + 64 + 32 + 8 + 4 = 236 (1).
55
Why: Reads the place values from the wrong end (the left-hand bit as 1), so the value is wrong.
5
Why: Counts the 1s instead of adding their place values.
Computer systems manipulate bit patterns.
Convert the hexadecimal number F4 to denary.
Award one mark for:
244
Why: 15 × 16 + 4 = 244 (1).
79
Why: Takes the right-hand digit as the 16s, so the value is wrong.
19
Why: Adds the two digits instead of multiplying the first by 16.
Computer systems manipulate bit patterns.
Convert the 8-bit binary two's complement pattern 1100 1011 to denary.
Award one mark for each of:
The correct answer is −53
−53
Why: The left-hand bit is worth −128: −128 + 75 = -53. Sign (1) and value (1).
53
Why: The value is right (1) but the minus sign is missing.
203
Why: Reads it as an unsigned number, so neither the sign nor the value is right.
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