 Let's talk a little bit more about assignment statements. Once again, to emphasize that the equal sign assignment operator is not the same as algebraic equality, here's an example that's totally valid in C, but not in algebra. After the first statement, the variable age contains the number 24. In the second statement, the right-hand side is completely evaluated, and the result goes into the variable on the left-hand side, replacing whatever used to be there. In general, updating variables is quite common. Presume that the variables in these examples have been declared elsewhere in the program. Whenever you have this pattern where a variable is updated by an arithmetic operation, you can use an augmented assignment operator. That turns these statements into these statements. I read them as age plus and becomes 1, limit minus and becomes 5, price times and becomes 0.9, amount divided becomes 2, and hours mod and becomes n minus 7. If you don't have a simple update, then you can't use augmented assignment. There's no way to simplify this expression using augmented assignment. Sorry, let's turn our attention to these statements where we're adding one, incrementing a variable, and subtracting one, decrementing a variable. Using what you now know, you can rewrite it this way. But because adding and subtracting one are such common operations in programming, C has a special notation for them. Use plus plus for increment and minus minus for decrement. This adds one or subtracts one from the variable without needing an equal sign. The variable is changed in place. The plus plus and minus minus follow the variable name, and we call this post increment and post decrement. You can also put the operator before the variable name as shown here, and then they're called pre-increment and pre-decrement. Why are there two versions and what's the difference? When the operators are all by themselves, there's no difference. Use whichever one you prefer. We'll examine the situation where there is a difference later in the course. For now, the important thing to remember is that when you are updating a variable, you can often change assignment statements like these into augmented assignment statements like these.