Discrete mathematics
Lesson 4 of 10
Standard practice
Graphs and counting
Objective. Use combinatorics and basic graph theory.
- 1. Learn
- 2. Worked example
- 3. Practice
- 4. Feedback
- 5. Continue
Learn: the key idea
Permutations count ordered selections, combinations unordered ones; a graph's degrees always sum to twice its edge count.
Concept mastery
Based on your past attempts at this lesson — the question types to practise again come first.
Complete a practice set to see your concept breakdown here.
Practice
Practice happens on its own screen, one question at a time. Answers stay hidden until you submit yours, and you can stop and pick up at the same question later.
Start practisingYour progress
Tick each step as you finish it. Your exact reading position is saved automatically, so Continue drops you back on the same line.
0 of 3 steps complete
Your place saves automatically as you read.