2. “The factorial of n is denoted by n! and calculated by the product of integer numbers from 1 to n”  For n>0, n! = 1×2×3×4×...×n  For n=0, 0! = 1 Huh?

3.  1! = 1  2! = 2x1= 2  3! = 3x2x1 = 6  4! = 4x3x2x1 = 24  5! = 5x4x3x2x1 = 120 You simply multiply the numbers of whichever “n” you have.

4.  Sherlock Holmes is investigating a crime at a local office building after hours. In order to enter a building, he must guess the door code.  If only one number opens the door, how many different ways can Sherlock open the door?

5. 1234512345 5 ways!

6.  If two numbers will open the door, list the different combinations of buttons that would open the door. (Assume no repetitions, i.e 3,3 ) Example: (1, 2), (1, 3), (1, 4)… 1,2 1,31,41,52,12,32,42,5 3,13,23,43,54,14,24,34,5 5,15,25,35,4

7.  How many ways could Sherlock open the door if two buttons will unlock it? 20 ways! How many possible choices? 5 Now, how many possible choices? 4

8.  If three numbers will open the door, list the different combinations of buttons that would open the door. (Assume no repetitions) Example: (1, 2, 3), (1, 2, 4), (1, 2, 5), (1, 3, 5)… 1,2,31,2,41,2,51,3,2… There has to be another way…

9.  How many different ways could Sherlock open the door if three buttons will unlock it? A grand total of 60 ways to unlock that door

10.  This does mean that if you now need to use FOUR buttons, it will be:  Again, the 5 does not mean you selected “button #5,” it means that you have 5 buttons to choose from. Since no repetition, then you would now have 4 buttons to choose from and 3 and so on.

11. Permutation: Number of arrangements when order MATTERS n = number of items r = number of choices a, b, c is DIFFERENT than a, c, b

12. …in a nice way, of course Please swap notes to check if your neighbor wrote down the following correct! n = number of items r = number of choices

13. n Factorial Number of Permutations N Factorial For any positive integer n, n! = n(n-1)(n-2)… 3.2.1

15. #7 The ski club with ten members is to choose three officers captain, co-captain & secretary, how many ways can those offices be filled? We can of multiplication and division

16. #11 In the Long Beach Air Race six planes are entered and there are no ties, in how many ways can the first three finishers come in?

17.  From this same worksheet,  ## 1 – 3 and 7 – 13 only  DO NOT forget that you need to have finished your graphs printed from online by Wednesday. This means that your calculations for your all equations need to be 100% correct. I will be available after school tomorrow for assistance.