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Practise 21 exam-style questions on Uses of hexadecimal for Cambridge IGCSE Computer Science (Paper 1). Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.
Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.
An HTML colour code such as #3A7BD5 is made up of six hexadecimal digits.
State how many bits are used to store the amount of each colour (red, green or blue).
8 bits (one byte) for each colour.
Each colour uses two hexadecimal digits, and each digit represents 4 bits, so each colour uses 2 × 4 = 8 bits. The whole code is 24 bits.
8 / eight (bits)
accept 'one byte'
When a computer program crashes, the computer may display an error code in hexadecimal.
Explain why error codes are displayed in hexadecimal rather than binary.
An error code in hexadecimal is much shorter than the same code in binary, so it is easier for a user or technician to read and write down, and they are less likely to make a mistake when reporting it or looking it up.
Error codes identify exactly what went wrong (often a memory location), and a technician has to look them up. A short hexadecimal code is far easier to copy correctly than a long string of 0s and 1s.
Hexadecimal is shorter than binary / uses fewer digits
max 2
Easier for the user / technician to read, write down or report
Fewer mistakes when the code is copied or looked up
The code can be converted directly back into binary / it often refers to a memory location
A designer wants text on a website to be pink. The colour has the denary values red 255, green 192 and blue 203.
Give the HTML colour code for this colour in hexadecimal.
255 = 15 × 16 + 15 = FF
192 = 12 × 16 + 0 = C0
203 = 12 × 16 + 11 = CB
HTML colour code: #FFC0CB
Convert each denary value into a two-digit hexadecimal number by dividing by 16 (the answer and remainder give the two digits). Keep the order red, green, blue, and write 0 as a digit so every colour has two digits - C0, not C.
Red: FF
accept lower case; final answer #FFC0CB, accept without the #
Green: C0
Blue: CB
the pairs must be in the order red, green, blue
Complete the statements about hexadecimal. Give the missing terms A to D, using terms from this list.
2, 4, 8, 16, binary, denary, longer, shorter
Hexadecimal is a base A number system. Each hexadecimal digit represents B bits, so hexadecimal is a C way of writing binary that is easier for humans to understand. Even when values are shown in hexadecimal, the computer still stores and processes them in D.
A: 16
B: 4
C: shorter
D: binary
Hexadecimal is base 16 and 16 = 2⁴, so each digit stands for 4 bits. That makes it a shorter, more readable representation of binary for people, while the computer itself only ever works in binary.
A: 16
B: 4
C: shorter
D: binary
Ready to try the rest? Every answer you write is marked against the mark scheme, so you can see exactly where the marks are.
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