Problem
Today we will study the method of finding the amount of combinations, or consecutive actions, or ways to select items from a bag which is called the Product rule. The main idea of this combinatorial is the following: if you are asked to perform an action that can be done in, say ways and another action afterwards that can be done in ways, then the total number of possibilities to perform two consecutive actions would be equal to . The reason for this is the opportunity to choose possible second actions for each of the choices of the first action already made before.