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Permutation and combination
Counting, without memorising nPr and nCr. Each concept lesson covers one idea, built from an everyday example. After every few lessons, we solve exam questions together.
8concept lessons, one idea each
3solve-together sessions
1practice sheet with every lesson
Lessons
- 1Does order matter?ConceptSoon
- 2Where nPr comes fromConceptSoon
- 3Why nCr divides by r!ConceptSoon
- Exam questions on lessons 1 to 3Solve togetherSoon
- 4When letters repeatConceptSoon
- 5When choices can repeatConceptSoon
- Exam questions on lessons 4 and 5Solve togetherSoon
- 6Sitting around a round tableConceptSoon
- 7Together, and never togetherConceptSoon
- 8Sharing identical thingsConceptSoon
- Exam-level mixed questionsSolve togetherSoon
Your turn
From lesson 1. Before each answer, ask: does order matter?