Lesson 3 Summary

 

Combinations can be used to solve counting problems where the order is not important. A combination can be represented by nCr or where n is the size of the group from which the objects are taken and r is the number of objects that are taken at a time. The following formula can be used to calculate a combination where 0 ≤ n ≤ r:

 

 

Many problems will require you to calculate multiple combinations and then apply the fundamental counting principle.