Algebra I

Real numbers are numbers that can be plotted on a number line. Before we learn algebra we need to make sure we're dealing with real numbers. Otherwise, we can't add, subtract, multiply and divide them.

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Hmm. So if there are real numbers, can there be unreal numbers? The answer is no. There can only be real numbers and things that aren't. There's no such thing as an unreal number. It's a weird concept, but welcome to math.

So how do you know if you're dealing with a real number if you don't have a number line. You can use your calculator. Enter into your calculator any number you can think of and press enter. If your calculator returns a value then you have a real number. If your calculator says undefined or not a number then you don't have a real number.