Arrangement
In mathematics, the arrangement is part of the enumeration analysis and is used, inter alia, in the probability calculation. When we choose k objects among n objects and the order in which the objects are selected is important, we can represent them by a k-tuple of distinct elements and we constitute an ordered list without any possible repetition. in which the order of the elements is taken into account. Such an ordered list is called an arrangement. The number of arrangements that can be made is noted and is worth: This formula can be understood by means of a tree of successive choices, since the first element is chosen from n, the second among ... and the last among . With the factorial notation, where n! = 1 × 2 × ... × n, this formula becomes while for k \u0026 gt; not.