Postfix notation
Using a common operator (plus, minus, multiply, or divide) will make the operator act from the first stack to the second stack. For example, the Reverse Polish Notation "12 3 /" means "take the numbers 12 and 3, then divide 12 by 3". On a Reverse Polish Calculator, this is written as "12 Enter 3 /", to denote each declared ranking up of the stacks.