Topic Index > TI 89 > TI 89 Combinations

The

**TI-89 Titanium graphing calculator**is a hand held calculator that helps you calculate many

**statistics and probability**problems in seconds. A

**combination problem**is one where a certain number of items are selected in order and that order doesn’t matter. While doing this by hand is cumbersome (the equation you use involves factorials: n!(n – r)!), the calculator can figure it out at the press of a button.

## TI 89 Combinations: Steps:

Watch the video or read the steps below:

**Sample problem**: If there are 5 people, Barb, Sue, Jan, Jim, and Rob, and only three will be chosen for the new Parent Teacher Association, how many combinations are possible for the committee?

**Step 1:** Press the HOME screen on the calculator.

**Step 2:** Press the CATALOG key.

**Step 3:** Press ALPHA 6. This selects the letter “n” and brings you to the “n”s in the list. If it doesn’t, try pressing ALPHA 6 again.

**Step 4:** Find **nCr(**. Press ENTER.

**Step 5:** Press 5. This is the number of possible people, or n.

**Step 6:** Press the comma, then 3. This is the number of people we need to choose, or r.

**Step 7:** Press ). The entry on your calculator should now read **nCr(5,3)**. Press ENTER. This returns you result. There are **10** possible ways this committee can be chosen.

**Tip**: Instead of hitting the ALPHA and 6 keys, use the scroll button to scroll through the menu.

**Tip**: Want to check your answer? Use our free, online combinations calculator and permutations calculator to check your work.

**Lost your guidebook?** You can download a new one from the TI website here.

Questions on TI 89 Combinations? Check out our FREE forum. Our resident stats guy will be happy to answer all of your tricky stats questions!

This was of great help for me in both nCr and nPr situations.