Probability and Statistics > 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.

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