Find the number of ways in which $5$ subjects can be arranged if each subject is allotted at least one period and no period remains vacant.
132143
organize 5 subjects in 6 periods
110856
Number of ways to select $K$ people from $N$ people such that at least $r$ people are there in between them
27610
Given the permutation $\sigma=\left(\begin{array}{ccccc} 1&2&3&4&5\\ 3&1&2&5&4 \end{array}\right)$
33862
Probability that the student can solve 5 of 7 problems on the exam
93572
How to determine if $n (n \geq 2)$ given numbers can be summed up to a certain number?
111609
Each $2\times 5$ rectangle contains $1\times 3$ rectangle
40852
Number of ways of distributing $n$ identical objects among $r$ groups
145102
Selecting A combination of minimum cost
43752
Is there a "quarter" equivalent for something divided in 9 pieces?
29887
Pigeon Hole Principle Problem I'm kind of lost for how to go about this.
4301
How many different arrangements?
155755
How many ways can you divide $9$ students into three unlabeled teams of $4$, $3$, and $2$ people?
151367
Probability of at least some number of heads
107964
Simple combinatorics problem.
32181
A logic puzzle involving a balance.
101930
Continuous numbering of questions in exam class
68882
Path to Combinatorics Problem [$1.11$]