Question

A student has 6 different notebooks and decided to give 5 of them to a friend. How many ways does he have to give away these notebooks?

Answer 1

As the order of notebooks does not matter, we'll count the number of combinations without repetition:

$N=\begin{pmatrix} 6\\ 5\end{pmatrix}=\\ =\cfrac{6! } {5! \cdot(6-5)! }=6.$