if you're in this set you cant fucking count

for the slow

stars and bars

star is the amount of objects, bars separate the options

if you had 5 marble to distribute across 3 kids you would have 5 stars and 2 bars

stars and bars equation

stars plus bars choose bars

n choose k

(n!/(n-k)!k!)

p(A|B)=

p(B|A)p(A)/p(B)

Set

Repeated elements ignored

Multisets

Can have repeated elements

Permutations equal #elements!/each repeat factorial

Mutually disjoint

No overlap is sets

P(AlB)

P(AnB)/B

Enumerated

elements are numbers/letters not variables