Help? Idk how to work the combination and permutation icon on my TI-30X IIS.?

Question

I'm gonna need this option for my Statistics class this semester and I was able to "accidentally" find a calculator with the appropriate icon, but i don't know how to enter in the info and get an answer... when i enter things and press enter it says, "domain error." Can someone tell me what is the correct way to enter the numbers.

Thanks!

Answer 1

Example with detailed "how-to"

Example Question: "Four different people are running in

a race. Use this formula to find how many different ways they can place 1st and 2nd.

FORMULA:  4 nPr 2 = x     [permutation question]

PRESS  "4"    "PRB"     "2"     "ENTER"

(answer is 12 different ways)

Example Question:"You have space for 2 books on your bookshelf. You have 4 books to put on the shelf. Use this formula to find how many ways you could place the 4 books in the 2 spaces.

FORMULA:  4 nCr 2 = x   [combination question]

PRESS  "4"    "PRB"   "RIGHT ARROW"   "2"     "ENTER"

(answer is 6 different ways)