What is a general formula for the permutation nPr in terms of n and r For instance if you have the permutation nP1 how do you find n?

Permutation Formula A formula for the number of possible permutations of k objects from a set of n. This is usually written nPk . Formula:

Example:

How many ways can 4 students from a group of 15 be lined up for a photograph? Answer: There are 15P4 possible permutations of 4 students from a group of 15. different lineups