CALCULATOR GUIDE
Factorials, Permutations, and Combinations:
| To evaluate a factorial | Example. 10! Answer. 3,628,800 |
| TI-84 Type the number first. The factorial key "!" is in the probability menu at MATH PRB. |
10 ! ENTER |
| TI-86 Type the number first. The factorial key "!" is in the probability menu at 2ND MATH PROB. |
10 ! ENTER |
| TI-89 Type the number first. The factorial key "!" is in the probability menu at 2ND MATH PROB. |
10 ! ENTER |
| To evaluate a permutation | Example. 10P4 Answer. 5040 |
| TI-84 Type the first number. Then hit the permutation key "nPr" in the probability menu at MATH PRB. Then type the second number and ENTER. |
10 nPr 4 ENTER |
| TI-86 Type the first number. Then hit the permutation key "nPr" in the probability menu at 2ND MATH PROB. Then type the second number and ENTER. |
10 nPr 4 ENTER |
| TI-89 Hit the permutation key "nPr" in the probability menu at 2ND MATH PROB. Then type the first number, comma, second number, close parentheses, and ENTER. |
nPr( 10 , 4 ) ENTER |
| To evaluate a combination | Example. 10C4 Answer. 210 |
| TI-84 Type the first number. Then hit the combination key "nCr" in the probability menu at MATH PRB. Then type the second number and ENTER. |
10 nCr 4 ENTER |
| TI-86 Type the first number. Then hit the combination key "nCr" in the probability menu at 2ND MATH PROB. Then type the second number and ENTER. |
10 nCr 4 ENTER |
| TI-89 Hit the combination key "nCr" in the probability menu at 2ND MATH PROB. Then type the first number, comma, second number, close parentheses, and ENTER. |
nCr( 10 , 4 ) ENTER |
Example 1. Evaluate 20P5 - 20C5
This expression is read as "20 pick 5 minus 20 choose 5". Use your calculator to evaluate it. The final answer should be 1,844,976. This is the difference between ordering mattering and order being unimportant when 5 objects are pulled from 20.
Probabilities and Odds:
| To evaluate a probability | Example.
 Answer. approximately 0.312 |
| TI-84/86 Remember that the ( ) containing a column of two numbers means a combination. |
( 15 nCr 7 * 10 nCr 5 ) / 25 nCr 12 ENTER |
| TI-89 Remember that the ( ) containing a column of two numbers means a combination. |
( nCr(15,7) * nCr(10,5) ) / nCr(25,12) ENTER |
Example 1. Evaluate 
TI 84/86: ( 15 nCr 5 * 10 nCr 7 ) / ( 15 nCr 7 * 10 nCr 5 ) ENTER
TI 89: ( nCr(15,5) * nCr(10,7) ) / ( nCr(15,7) * nCr(10,5) ) ENTER
The final answer should be the repeating decimal 0.22222... Did you get it? Note that parentheses are required around the entire denominator since there was more than one combination in the denominator.
Originally written: 2005-09-01
Last revision:
2007-09-19 05:50 PM
