A computer stores a colour as a 24-bit binary pattern.
The programmer writes the colour in hexadecimal rather than in binary. Explain one reason why.
Mark scheme
Award up to two marks for a linked explanation such as:
- Hexadecimal is shorter/has fewer digits than binary (1) because each hexadecimal digit represents 4 bits/a nibble (1)
- Hexadecimal is easier to read/write (1) because there are fewer characters/digits to enter (1)
- Hexadecimal is easier to convert to and from binary (1) because four binary bits map to one hexadecimal digit (1)
For both marks, the expansion must follow/associate with the statement.
Allow the 24-bit colour as the linked reason, e.g. a 24-bit value can be written as only 6 hexadecimal digits (1).
Do not accept 'easier'/'simpler' on its own: naming what is easier, such as easier to read/write, is the first mark, but the second mark needs a linked reason.
Only credit 'fewer digits/characters' once, as the reason for one point; do not award it again as the reason for a second point.
Do not accept that hexadecimal uses less storage space/memory than binary, or that it is more compact to store; the same number of bits is stored.
Example answers and how they were marked
Hexadecimal is shorter than binary because each hexadecimal digit represents 4 bits, so the 24-bit colour needs only 6 hexadecimal digits.
Why: Gives the point that hexadecimal is shorter (1) and links it to each hexadecimal digit representing 4 bits, using the 24-bit colour as the linked reason (1).
Hexadecimal is easier to read than binary.
Why: Names what is easier to read (1) but gives no linked reason such as fewer digits to enter, so only one mark.
Hexadecimal is used because it takes up less storage space than binary.
Why: The same number of bits is stored in either notation, so this is a misconception and earns no mark.