LET’S TRY ONE
A group of 2 people is chosen from 5 people. Order does not matter. How many different groups are possible?
10
Use combinations: 5! / (2! × 3!) = 10. Each unordered group is counted once.
Learning steps & teaching tips
Count selections where order does not matter.
- Contrast a chosen group with an ordered lineup, then use the combination count.
- Work through the example and explain why each operation is used.
- Estimate or use another method to check the result before choosing.
Try it together
Work with a partner: solve one example, explain the method, then change one number and predict what changes.
Contrast a chosen group with an ordered lineup, then use the combination count.