How do you do permutations and combinations? - Answers

permutations imply that the order is important where as a combination implies the order is not important. In many calculators there are buttons which can calculate the combination or permutation for you. in my calculator, (TI-84) press the math button, then go to probability and you will see a list. one is nPr. this is the button for a permutation. you first enter the total amount, then push the buttons to get nPr, then enter the number you are choosing out of the total. press enter and the answer will appear on the screen. The combination is found and entered similarly (nCr). An example of a permutation is the number of ways you can line 6 people in a row (order is important) 6 nPr 6 is what you should type in your calculator. the calculator performs a process calculation 6x5x4x3x2x1. it does this because there are 6 options for the first spot, 5 options for the second spot (since one is already in the first), 4 options for the third spot, and so on. the answer to this question is 720. An example of a combination is saying that there are 3 identical prizes in a raffle. 10 people are in the running for the raffle and 3 will be winners. it is not important in what order the contestants are drawn since the prizes are the same. you should enter 10 nCr 3 in your calculator and the answer will be 120. I hope this helps you! I typed a long answer not because it is complicated, but because I want you to be able to understand it and gave a thorough answer Summary: Permutations are used when order is important and combinations are used when order is not important. Graphing calculators offer buttons that will do this all for you (on a TI-84 press MATH-go to column PRB- option 2 (nPr) is for permutations and option 3 (nCr) is for combinations. Good Luck!