- Intro to Combinations and Permutations
- Permutations with Repetition
- Permutations without Repetition
- Permutations Formula
- Android Lock Screen
- Tigers and Bears - Oh My
Combination without Repetition
- Combination Formula
- Combining Combinations
The String of Beads
- Combinations with Repetition I
- Combinations with Repetition II
To calculate permutations, you multiply by the number of possible elements each time. You can do the same thing for groups of elements. For example, if you need to choose fruit and snack for your lunch, you can just multiply the possible fruit combos by the snack combos to get the total number of possible combinations. This is because for each fruit combo, you can try any possible snack combo.
Sometimes the choices have limitations and you need to pick between two different options, such as A and B. In such a case, you need to add the A possibilities to the B possibilities to get the total number of possibilities.
You are packing a suitcase for a trip. You need to pack 7 from 10 shirts and 4 from 8 pairs of pants.
In addition, you want to take 3 fruit or melons (to eat). You have 2 melons and 4 other fruit. You can take any fruit combination except for 2 melons together.
* No 2 melons together.