New posts in Combinations

Confusion in the solution for this question

How to calculate a combinatorial sum

Sitting younger, older alternately.

A unique question in combinatorics and non-commutative variables.

In how many ways can 4 cards be drawn randomly from a pack of 52 cards such that there are at least 2 kings and at least 1 queen among them?

Number of matrices with determinant value $0$

3 balls are distributed to 3 boxes at random. Number of way in which we set at most 1 box empty is:

No. of positive integral solutions and link to coefficients in expansion

Coin Flip Problem

Combinations of elements from multiple sets with constraints