The **TI-89 Titanium graphing calculator** is a hand held calculator that helps you calculate many **statistics and probability** problems in seconds. A **permutation 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.

**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 , 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.