choosing $5$ non consecutive books from a shelve of $12$
24091
How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers?
153072
Guessing a subset of $\{1,...,N\}$
110856
Number of ways to select $K$ people from $N$ people such that at least $r$ people are there in between them
45504
Best way to select a subset of items in a long list
157621
Combinatorics involving picking a specific amount of consonants without repeat and vowels (can repeat)
89719
Probability of selecting a non-measurable set
130640
Chance of selecting the last k pages in correct order from a set of n pages
109826
Probability of list having a pair of unchanged consecutive elements once ordered
126156
An instructor has an exam of 5 questions and a question bank of 50 questions. Are there $50\choose 5$ or $(50)_5$ possible exams?
158708
Counting the adjacent swaps required to convert one permutation into another
96663
Mathematical expectation of picking cards of the same value from a standard 52-card deck
150281
Am I on the right track to figure out this combinatorics problem?
151466
Series of consecutive numbers (different lengths)
69827
Set conditions at a permutation
57644
Lower bounds for ${{2n} \choose {n}}$
31708
Divisibility criteria for $7,11,13,17,19$
60615
Product of $5$ consecutive integers cannot be perfect square