Computer Fundamentals and Number Systems
What this domain tests
This domain checks whether you can describe how a computer takes data, processes it and produces information, and whether you can move confidently between binary, octal, decimal and hexadecimal. Expect definitions of hardware/software, units of storage, and conversion questions with written working.
Core rules
- Data is raw facts; information is processed data that supports a decision.
- The input–process–output–storage cycle describes any computer task.
- 1 byte = 8 bits. In binary-based storage, 1 KB = 1024 bytes, 1 MB = 1024 KB, 1 GB = 1024 MB.
- Binary is base 2, octal base 8, decimal base 10, hexadecimal base 16 (digits 0–9 and A–F).
- Decimal to binary: divide repeatedly by 2, read remainders upwards.
- Binary to octal: group bits in threes from the right; binary to hexadecimal: group in fours.
Worked example
Convert decimal 45 to binary and hexadecimal. 45 ÷ 2 = 22 remainder 1; 22 ÷ 2 = 11 r 0; 11 ÷ 2 = 5 r 1; 5 ÷ 2 = 2 r 1; 2 ÷ 2 = 1 r 0; 1 ÷ 2 = 0 r 1. Reading upwards: 101101₂. Check: 32 + 8 + 4 + 1 = 45. Group from the right in fours: 0010 1101. 0010 = 2, 1101 = D, so 2D₁₆.
Traps
- Do not write 1 KB = 1000 bytes when the question uses binary units.
- Read remainders from bottom to top, not top to bottom.
- Hex uses single symbols A–F; “10” in hex is not ten.
- Keep leading zeros when grouping for octal or hex.