Find out how many different ways you can choose items. For an in-depth explanation of the formulas please visit Combinations and Permutations. Names. o Calculate the number of outcomes of a random experiment using . have three remaining possibilities for each of the preceding results-- calculate the product. Find the number of combinations and/or permutations that result when you choose r elements from a set of n elements. For help in using the calculator, read the. Name your Custom Course and add an optional description or learning objective. Consider the example from the previous paragraph. Want to watch this again later? We can use the calculate possibilities formula, where the number of permutations of n objects www stargames net k at a time is written as n P k. If none of the questions addresses your need, refer to Stat Trek's tutorial on the rules of counting or visit the Statistics Glossary.