New posts in Combinations

How many $5$-digit numbers with distinct digits are divisible by 3 (and generalize)

$10$ letters are placed in $10$ addressed envelopes. Find the number of ways such that at most three letters are not in correct envelopes

What is the domain of a division of functions?

GRE combinatorics question about counting the no. of sets questions satisfying a certain requirement.

Number of surjective functions from a set with $m$ elements onto a set with $n$ elements

The pigeonhole principle and a professor who knows $9$ jokes and tells $3$ jokes per lecture

Euclidian plane $\pi$ with all points either red, green or blue

The four basic combinatoric formulas?

Proof of solutions to “24” operations game

Find the number of ways so that each boy is adjacent to at most one girl.