10 (one-zero), which represents denary 16; the digits restart and a new place value column begins, just as 9 rolls over to 10 in denary. Learn it step by step →
Data Representation is a core part of A-Level Computer Science. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
BinaryBase-2 representation using only 0s and 1s.
HexadecimalBase-16, a shorthand for binary (0–9, A–F).
Bits & bytesA bit is one binary digit; 8 bits make a byte.
Character encodingASCII and Unicode represent text as binary codes.
Image representationImages stored as pixels with a colour depth.
Sound representationSound sampled at a rate and bit depth to store digitally.
What your exam board covers
Where Data Representation sits in each exam board's specification. Tap a board to see what it lists.
Questions where students often pick the tempting wrong answer — make sure you know the right one:
What comes after F when counting in hexadecimal?✗ G - the alphabet simply continues after F.✓ 10 (one-zero), which represents denary 16; the digits restart and a new place value column begins, just as 9 rolls over to 10 in denary.
Does doubling the colour depth of an image double the number of available colours?✗ Yes - twice the bits means twice the colours.✓ No - each extra BIT doubles the colours, so going from 8-bit to 16-bit multiplies the available colours by 2^8 = 256, not by 2.
Compared with ASCII, Unicode:✗ Uses fewer bits for every character✓ Can represent characters from far more of the world's writing systems
Practise Data Representation — free games
Test yourself with these quick revision games for this topic:
