ASCII uses 7 bits to store each character. A system has only 6 bits available to store each character.
State the number of different characters the system can represent.
Mark scheme
Award one mark for:
- 64 (1)
- 2^6 (1)
- 2 × 2 × 2 × 2 × 2 × 2 (1)
Allow 64 characters / sixty-four.
Allow 2 to the power of 6 for 2^6.
Do not accept 128, which is the number of characters that can be represented using 7 bits.
Do not accept 63, the largest value that can be represented using 6 bits, rather than the number of different characters.
Do not accept 12 (2 × 6), ie the number of bits multiplied by 2.
Example answers and how they were marked
64
Why: Correct: 2^6 = 64 different characters (1).
128
Why: Scores 0: 128 is the number of characters that 7 bits can represent, not the 6 bits the system has; the Do not accept line applies.
63
Why: Scores 0: 63 is the largest value 6 bits can hold, not the number of different characters; the Do not accept line applies.