Addition, subtraction, division, and multiplication are the four basic math operations that are easy to do with two operands. Also, when we want to add three numbers together, we do it step by step, starting with the first two numbers and adding their answers to the third number. So, all of the basic math operations in your textbook, which are called "binary operations," are the same thing. The word "binary" means "two." Let's take a set A whose elements are x, y, and z as an example. When we do operations on x and y, the results will also be in the same set, which is A. So, operations that are done on a set A are said to be binary operations.