What would you like to understand?

The number of ordered r-item selections from n distinct items without repetition is given by the formula $n!/(n-r)!$. This represents the product of the first r terms of the descending sequence starting from n.

Conditions: The items are distinct.; Selection is without repetition.; The order of selection matters.; $r$ is a non-negative integer less than or equal to $n$.

The number of ordered r-item selections from n distinct items without repetition is given by the formula $n!/(n-r)!$. This represents the product of the first r terms of the descending sequence starting from n.

Conditions: The items are distinct.; Selection is without repetition.; The order of selection matters.; $r$ is a non-negative integer less than or equal to $n$.