# TI-84 Calculator – 28 – Permutations, Combinations, Factorials

how to do combinations on ti 84 This is a topic that many people are looking for. cfiva.org is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, cfiva.org would like to introduce to you TI-84 Calculator – 28 – Permutations, Combinations, Factorials. Following along are instructions in the video below:
And welcome to this section of the ti 84. Tutor and in this section. We were going to work with probability or begin to work with probability.
And so this section specifically were going to talk about permutations combinations. Factorial and were going to talk about random numbers. And so the thing that you need to keep in mind is that most of the probability functions are in the math menu.
And theres a menu over here called probability. So lets go look at that and then here you have several things that are going to be useful. The first one is generating a random number a lot of times youre dealing with statistical things or things in probability.
And you want to generate a quick random number so you can hit number one and a random number is going to you know the little expression is going to pop up. There you hit enter and out is going to spit. A random number between 0.
And 1 in probability all of your probabilities are going to be between 0. And 1. So its useful to be able to generate random numbers maybe youre doing a little experiment.
Your calculator who knows. But if you ever need a random number generator. There it is now once you put it up.
There you can continue generating random numbers by continuing to hit enter notice. Im not putting the command. There anymore.

But the calculator is smart enough to know that if i generate one random number. Im probably going to want to generate a few more so if you keep hitting enter you keep giving random numbers. Now if you go back into the math menu and back to probability look down.
Lets skip around number. 5. Random integer so lets go to number 5 and here for a random integer.
Its exactly what it sounds like im going to get a random integer out. But you need to specify a boundary maybe i want random integer between 0. And 10.
So i need to put two numbers in there separated by comma comma and whenever i do that heres a random number theres one i can hit it again your zero six nine. So its generating random numbers between zero and ten inclusive but go back in the math menu and go back to probability. And i go back to random integer number five.
I can put anything i wanted here between 2 00 and 77. And then its only going to generate random numbers between those two numbers. So theres 22.
Theres 11. Theres 5 you see the point here so you can generate put any numbers that you want in here. Now.
If we also go back into the math menu and go into the probability menu. Were going to see our nice friendly factorial. I kind of wish they would have put a button on the calculator a dedicated button for this but i guess i see why they didnt do it as well.

But if you ever need to do a factorial of a number lets say. 4 factorial put your 4 up there and then go into math menu you have to go to probability and hit number 4 put that exclamation point there thats 4 factorial you hit enter and youll get a number of 24. So dont forget that factorial just means so in this case.
4 times 3 times 2 times 1. So 4 times. 3.
Is 12 and 12 times. 2. Is 24.
And thats why we get that so you know a larger number is much more difficult to do in your head. So 255 factorial number. 4.
It would equal a very large number. Its that like its so large its too big for the calculator to display. So you can quickly get up to the point where its not going to work.
But i can pull up the last entry and i can go back here maybe ill delete a decimal and ill make it 25 factorial and that it can sort of do 15. Times. 10 to the 25.
Very very large number because this is basically 25 times 24 times 23 times 22 times. 21. You know all the way down to 1.

So thats a huge number ok now two other very important functions in this calculator and probability that youll use all the time is number two and number three which is permutation and combination you can calculate both of them by hand. Theyre formulas that you can do to calculate by hand. But having a calculator is all about saving a little bit of time so.
If you know how to use these. Its going to save you time in order to use either one of these things you need to put a number in for in and a number in for r. So heres the total amount of items you have and this number is how many you are pulling out of that bag at one time and if this these concepts dont seem very clear to you then its a good idea for you to go take a look at my probability.
And statistics tutor where we talk about permutations and combinations and in great detail and all the different examples of why you would use them. But if you ever did need to use them the way you do it is is this you get out of here. Lets say you wanted to do a permutation of five things taken two at a time.
So you would put five things first then you would go to the probability menu and then you would hit number two and thats going to put npr up there and then two you have to put there because were taking two at a time so we have five items in a bag. And were taking two at a time out of this bag. And then whenever we hit enter the calculator has told us that there are 20 different permutations for that to happen.
And dont forget permutations are when you pull random objects out for instance and the order does matter. So if youre pulling a yellow sock and a red sock out it does matter. If you pulled a yellow and then a red or if in a different experiment.
You pulled a red and then a yellow. Its the same two socks that you pulled out. But the order in which you pull them out matters and so thats the number of permutations that you can pull two items out of the bag of five objects now if you wanted to calculate the number of combinations.
You would put five and then you would go into the math menu two probability and then do number three and they would take them two at a time. Lets say so heres the number of combinations of five things taken two at a time if you hit that youll get a number of ten and so in this case. Its the same experiment.

Five items in a bag you take two of them out at one time. Its just that in this case. Four combinations.
The order does not matter. So if i pull a red sock and a yellow sock out of the bag. It doesnt matter.
Which one comes first you know red followed by yellow is the same thing as yellow followed by red. Its counted the same so because theres no matter in what order in which you pull them out of course. The combinations for the same numbers.
The combination is going to have less number of ways in which that can happen because when the order does matter of course. Theres a whole lot of different ways in which you can those socks out of a bag for instance. So those are the basic ideas of using these functions in the calculator.
Just remember. If you want to generate a random number thats here between 0 1. If you want to generate a random integer.
Then you need to put two numbers separated by a comma and its going to generate a random integer between those two points. Factorial is here you just stick the exclamation point after your number and then permutations and combinations are also in here. But its important the main thing people get confused about is in order to use permutations of combinations.
You have to stick the first number on first then go to the probability menu then hit you know your npr or ncr and then hit your other number and then evaluate the expression. A lot of people try to do it. Where they go put this up first in the problem.
So remember first number then function then second number. It should really match the labeling here and youll be in really good shape. .

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