← GCSE Computer Science

D03 3.3.2 Binary ↔ hex and decimal ↔ hex conversion (0–255 / FF)

Currently Developing · last touched 2026-10-20

Binary route holds (6 and 14 Oct). Secure on an unaided set of hex↔binary and hex↔decimal items on one day; short route (left digit × 16) optional, not a replacement — 2F gave 182 on 15 Oct.

Every change

WhenChangeEvidenceSession
2026-10-20Developing → Developingadjudicated paper #9 Q14: 3/3, why:bar, at the bar (E6→230 via the bit pattern, working written; 01011101→5D). 6 Oct's B7→183 was one item, not the set the secure bar asks for, and 2F→182 on 15 Oct (short route) sits between: no move.standalone
2026-10-15Developing → Developing15 Oct: hex->decimal short route shown once (E6 = 14x16+6 = 230) after she used the binary route on paper #9. 2F unaided: 'f = 15, 15*12 = 180, 180+2 = 182' - right digit multiplied, and by 12 not 16; 47 shown with the binary check 0010 1111. Binary route not tested today. Stays developing.session 108
2026-10-14Developing → Developingpaper #9 Q14: 3/3, loss=none — E6→230 with working via 1110 0110, 01011101→5D; 5 min on a 3-min guidesession 106
2026-10-06Developing → Developing6 Oct, 1 day on, by hand in pen, photographed (set 14:24, agreed 14:29, photo 14:27): B7 -> B = 11 = 1011, 7 = 0111, 10110111 = 128 + 32 + 16 + 4 + 2 + 1 = 183. 1/1 unaided with no check prompt; a crossing-out sits before 0111. One item, not the set the secure bar asks for; stays developing.session 79
2026-10-05Developing → Developing5 Oct, by hand in pen, photographed at the agreed time (set 13:09, photo 13:14). Self-check first: which is 12, 1100 or 1010 -> 1100, unaided. 9C to decimal: wrote 9 = 1010, C = 12 = 1100, 10101100 = 128 + 32 + 8 + 4 = 172, wrong (156). Asked only to add up the bits written for 9: second photo 13:18 shows 1010 crossed out, 1001, 10011100 = 128 + 16 + 8 + 4 = 156. 1/2 unaided, 2/2 after one check prompt. Bar: points-marked, secure about 80% unaided; stays developing.session 73
2026-10-02Developing → Developing2 Oct, later session, by hand on paper, photographed, working shown, no route displayed; bar: points-marked, secure about 80% unaided. 11010110 -> D6; 5E -> 01011110; 200 -> C8 via binary with a does-it-fit grid, written joined; 9C -> 154, wrong (156): wrote C = 12 = 1010 although 1100 = 12 = C is right in the 200 item. 3/4 unaided = 75%, under the secure bar; hex to decimal is the direction that failed. Stays developing.session 68
2026-10-01Not started → Developingtaught / confirmed / applied, 1 Oct. Teach 4/4 (D → 13, 1011 → 11, 11 → B, 0100 → 4). Confirm: two say-backs in own words (split down the middle; add each side, write the hex equivalent), guided 01111010 → 7A. Apply unaided: 11001111 → CF with both sums; A6 → 1010 0110; 2F → 47 via 00101111; 172 → 10101100 → A and C in two set steps. 4/4 values right, typed. notstarted → developing, one level.session 61
2026-09-29Not started → Not started29 Sep: opened only — 16 symbols and 'one hex digit = four bits' stated; first check (D → 10, 1011 → 11) set and not answered, session stopped. Untaught.session 58
2026-09-28Not started → Not startedPlacement Q4 skipped. 0/2, 28 Sep. Untaught.session 53

In papers

AttemptPaperQMarksNote
Exam practice — week 42 · maths, lit, cs — GCSE Computer Science sectionexam-skills #9143/33 of 3. Part 1: 230, with working via the bit pattern 1110 0110 then place values (working written). Part 2: 5D. 5 min on a 3-min guide — the detour through binary for part 1 is longer than 14×16+6 but valid.
Placement — Computer Science paper 2 (theory) — GCSE Computer Science sectionexam-skills #240/2skip. 0/2. D03 untaught.

Materials

Craig'n'Dave: Converting between decimal and 2-digit hexadecimal
Binary to hex and decimal to hex, up to FF.
video
Teach-ICT: Hexadecimal
Binary/decimal to hex conversion.
notes
PMT: Fundamentals of Data Representation (notes and questions)
Free, no login. Retrieval layer after teaching.
practice
AQA 8525 specification v1.3 (first teaching Sept 2025, exams June 2027 onwards)
THE document to teach to. Sections 3.1–3.8 are the syllabus; the right-hand 'additional information' column gives the depth limits. Verified 5 Sep 2026.
notes
AQA Summary of changes (8525), June 2025 — what was removed for 2027
Removed: Von Neumann as a named model, optical storage, LAN topologies, Ethernet, Wi-Fi, UDP, FTP, alternative link-layer names. Void these questions on any 2022–2026 paper.
notes
AQA 8525 overview page (specs, teaching guides, sample papers)
Stable entry point if any file link below dies. Lists both spec versions and the 2027 sample materials.
other
AQA subject-specific vocabulary (first exam 2027)
The terminology examiners expect. Use for retrieval starters and to check definitions in written answers.
notes
AQA Notes and guidance: Pseudo-code (8525/1)
Every algorithm in a question paper uses this pseudo-code. She must READ it fluently; she need not write in it.
notes
AQA Notes and guidance: Python (8525/1)
The exact Python style AQA uses in question papers and mark schemes. Use if Python 3 is the chosen language.
notes
AQA Notes and guidance: C# (8525/1)
The exact C# style AQA uses in question papers and mark schemes. Use if C# is the chosen language.
notes
AQA Notes and guidance: VB.NET (8525/1)
The exact VB.NET style AQA uses in question papers and mark schemes. Use if VB.NET is the chosen language.
notes
AQA Notes and guidance: 8525/1 Marking guidance (coded solutions)
FOR THE MARKER. AQA's examiner rulebook: logic over syntax, indentation rules per language, design marks, meaningful variable names, typing rules, records. Read before marking any code question. Verified 5 Sep 2026.
notes
Specimen Paper 1 (Python) 8525B/1 — sample assessment materials
Official specimen, 90 marks, 2h. Paper 1 content unchanged for 2027, so fully usable. Handwrite the code answers.
paper
Specimen Paper 1 (VB.NET) 8525C/1 — sample assessment materials
VB.NET variant of the same specimen. The C# variant (8525A/1) is on the AQA assessment-resources page.
paper
Specimen Paper 1 mark scheme (all three languages) 8525/1
Mark against the section for her language only. Shows the 'Mark A/B/C' feature-marking and 'max N if any errors' caps.
paper
Sample Paper 2 question paper — Sample set 1 (first exam 2027) 8525/2
The ONLY official Paper 2 on the 2027 content. Use as the first full Paper 2 mock. 90 marks, 1h45.
paper
Sample Paper 2 mark scheme — Sample set 1 (first exam 2027) 8525/2
Contains the level-of-response band descriptors and flags the Von Neumann question as no longer asked from 2027.
paper
June 2023 Paper 2 question paper 8525/2 (legacy spec)
LEGACY: void any question on Von Neumann, optical storage, topologies, Ethernet, Wi-Fi, UDP, FTP and reduce the maximum before marking.
paper
June 2023 Paper 1 (VB.NET) question paper 8525/1C (legacy spec)
Paper 1 is unaffected by the 2027 changes. The 1A (C#) and 1B (Python) variants of the same paper are on the AQA past-paper finder.
paper
June 2023 Paper 1 mark scheme 8525/1 (all languages)
Covers 1A, 1B and 1C. Note the examiner 'I.' (ignore) lists — the compile tolerance in practice.
paper
June 2023 Paper 1 examiner report 8525/1
What real candidates got wrong. Key lines: design marks exist even for wrong code; attempt every coding question; the indentation grids are misused.
notes
June 2022 Paper 1 mark scheme 8525/1 (all languages)
Legacy but Paper 1 content is unchanged. Question paper via the past-paper finder.
paper
AQA past-paper finder (2022–2024 papers, mark schemes, examiner reports, modified papers)
Search 8525. The most recent series (2025, 2026) are login-gated for about a year — ask the exam centre. 2027 is the first series on the new content.
other
AQA 8525 assessment resources page
The file list renders in-browser only. Filter by 'Sample papers' for the C# specimen (8525A/1).
other
AQA GCSE grade boundaries — June 2024 (contains 8525A/B/C rows, out of 180)
Legacy proxy only. The tracker holds the 8525C row. Look up 8525A or 8525B here once the language is chosen. No 2027 boundaries exist until August 2027.
other
AQA GCSE subject grade boundaries — June 2025
Most recent legacy series. Directional only.
other
AQA GCSE exam timetable May/June 2027 (version 1.0)
8525/1A/1B/1C Monday 10 May 2027 am; 8525/2 Wednesday 19 May 2027. Confirm with the centre.
other
AQA private candidates page
PARENT: the centre must sign the Practical Programming Statement (spec 5.1) and declare the Paper 1 language at entry. Confirm both in writing early.
other