Counting Formulas Flashcards
1
Q
Combinations Formula
Permutations of n items
A
2
Q
Permutations of r items out of n items:
A
3
Q
Permutations of n items arranged in a circle
A
4
Q
Combinations
C(n,r) - Select r things from n items
A
5
Q
Combination with repetition
(Selecting n things from r types of things)
A
6
Q
Number of handshakes among n people
A
7
Q
Circular Handshakes
(only shake with immediate neighbors on your left and right)
A
8
Q
Distribute n identical items into r groups
A
(Stars And Bars) / Sticks And Stones
9
Q
(Bowling Pin)/Triangular Numbers
Formula for n-th triangular number
A
