Tips on Factorials with/without the Calculator
0! = 1
1! = 1
2! = (2)(1) = 2
3! = (3)(2)(1) = 6
4! = (4)(3)(2)(1) = 24
5! = (5)(4)(3)(2)(1) = 120
Make sure you do NOT cancel factorials as in:
This is a common mistake.
The correct method is:
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Find (4,3):
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Find C(20,5) =
Calculators:
The following instructions are for the Graphic TIs.
1.
Find C(16,5) = 4,3682. Find P(16,5)= 524,160
The arrow illustrated below, is on the upper right hand side of all the TI calculators.
TI 81, 82 and 83.
1. 16 Math 
#3 enter 5 enter
2. 16 Math #2 enter 5 enter
TI 85 and 86.
2nd Math F2
1. 16 F3 5 enter
2. 16 F2 5 enter