2.3 Systematic listing strategies — Practise
Work independently, then use the checked solutions to review your method.
- A badge has one of two shapes, circle or star, and one of three colours, red, blue or green. List all possible badges.
- List all three-digit numbers made from , using each digit once.
- A snack can be a yoghurt or a biscuit, with water, juice or milk. List every snack-and-drink choice.
- A journey has a choice of two trains, A or B, and one of two buses, X or Y. List the possible train-and-bus pairs.
- List all two-digit numbers made from without repeating a digit.
- There are three paths from A to B and two paths from B to C. List the route choices from A to C using labels A1, A2, A3 and B1, B2.
- Three runners, Ana (A), Ben (B) and Cal (C), finish first, second and third with no ties. List all possible finishing orders.
- Using digits once each, list the three-digit numbers that are even.
- A menu has two starters (soup, salad), two mains (rice, pasta) and two desserts (fruit, cake). List the meals with salad and fruit.
Answers and concise solutions
1. Badge outcomes
Answer: Circle-red, circle-blue, circle-green, star-red, star-blue, star-green.
2. Three-digit numbers
Answer:
3. Snack and drink choices
Answer: Yoghurt-water, yoghurt-juice, yoghurt-milk, biscuit-water, biscuit-juice, biscuit-milk.
4. Journey pairs
Answer:
5. Two-digit numbers
Answer:
6. Route pairs
Answer:
7. Finishing orders
Answer:
8. Even numbers
Answer: and ; an even number must end in 2.
9. Meals with salad and fruit
Answer: Salad-rice-fruit and salad-pasta-fruit.