IA idea · Games & puzzles
How many positions does a Rubik's Cube have?
Research question
Why does a 3×3×3 Rubik's Cube have exactly 43,252,003,274,489,856,000 reachable positions, and how many does a 2×2×2 cube have?
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Why it makes a good exploration
The count comes from permutations and orientations with three constraints that make most arrangements unreachable. Deriving it is a satisfying exercise in counting principles — and you can check the constraints on a real cube.
The mathematics you'll need
- Permutations and factorials
- The multiplication principle
- Parity and orientation constraints (explain)
- Applying the same reasoning to the 2×2×2
Where the data comes from
Use a real cube to demonstrate the constraints (e.g., a single twisted corner cannot be solved).
- OEIS (On-Line Encyclopedia of Integer Sequences) — Check a sequence you have found and read its known formulas and references.
A possible outline
- Count arrangements of corners and edges.
- Explain each constraint with a physical demonstration.
- Derive the final count.
- Apply to the 2×2×2.
- Reflect on God's number (20) and what it means.
Pitfalls that cost marks
- Stating constraints without justification.
- Arithmetic errors with huge numbers — use exact arithmetic.
- Confusing positions with move sequences.
Showing personal engagement
- Demonstrate the constraints with your own cube.
- Compare with a 4×4×4 conceptually.
- Estimate how long it would take to visit every position.
See Criterion C: personal engagement for what examiners look for.
Which course is it for?
| Course | Fit | Maths to lean on |
|---|---|---|
| AA SL | Fits — ambitious at SL | Permutations and factorials; The multiplication principle |
| AA HL | Good fit | Permutations and factorials; The multiplication principle |
| AI SL | Not a natural fit | The mathematics is mainly AA or HL (calculus or proof beyond AI SL); an AI SL version would need a data-driven, technology-based approach. |
| AI HL | Not a natural fit | The mathematics is mainly from the AA course; an AI HL version would need modelling with technology, statistics or networks at HL level. |
Level: Ambitious. Suits confident students; expect to learn some mathematics on your own. See how the IA differs between AA and AI, SL and HL.
How this idea reaches the top bands
Reflection (D)
For this idea, start with the weak points: stating constraints without justification; and arithmetic errors with huge numbers — use exact arithmetic. Say how each one affects your answer.
Use of mathematics (E)
SL: permutations and factorials; the multiplication principle; parity and orientation constraints (explain); applying the same reasoning to the 2×2×2, each explained in your own words and carried out correctly.
How games & puzzles explorations reach the top bands in general: Games & puzzles IA ideas. Guides: A · B · C · D · E · self-grade sheet.
Taking it further
Show why corner orientations must sum to a multiple of 3 by tracking a single move.
Extending it for HL
Add an HL technique the question genuinely needs: what an HL games & puzzles exploration adds.
See a complete IA, marked
How long does a game of Snakes and Ladders last on my grandmother's board? (AI HL) is a complete games & puzzles exploration, marked on every criterion.
Frequently asked questions
Which IB Maths course is this IA idea for?
It works for AA HL and AA SL. We rate it Ambitious: it suits confident students, who should expect to learn some mathematics on their own.
What mathematics does this IA use?
Permutations and factorials, the multiplication principle, parity and orientation constraints (explain) and applying the same reasoning to the 2×2×2.
Where can I get data for this IA?
Use a real cube to demonstrate the constraints (e.g., a single twisted corner cannot be solved). Checked sources and tools: OEIS (On-Line Encyclopedia of Integer Sequences).
Turn this idea into your IA
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