Okay. So in this lesson, we will start to look at some elementary R commands. I know some of you taking this class may not have any programming experience and some of you might have extensive programming experience. But for those of you who do not have any experience in programming in any language, please don't worry. In this class, the level of difficulty will be about the same as writing a function in Microsoft Excel. We'll be taking baby steps along the way, and feel free to pause the video at any point in time in case you want to look over your notes. So let's begin. The first thing I'd like to talk about is using R with mathematical functions, almost like a calculator. So for this lesson, I'm going to focus mostly in the console area. So I'm going to maximize this screen. There we go. I think I've showed you, in previous video, some basic commands like 2 plus 4. So that's addition, and we're rolling. Subtraction is with the hyphen. So we can use 3 minus 5, and that's minus 2. We can obviously do multiplication, 3 times 3 is 9. So far so good. Division is with a slash, so 5 over 2 is 2.5. If you want to do an exponent, for example, two to the third power, 2 times 2 times 2 that would be 8. Another way to write the same thing is to use two, and then instead of one asterisk, use double asterisk, two to the third power, and that is also eight. So those are your basic arithmetic functions, but you might want to go beyond that and use more complicated functions that you might have learned in the past. So we can take the absolute value of a number which essentially strips away the sign. So the command there is abs minus 7, say, I typed a 5, hit Enter, and the absolute value of minus 5 is 5. So one thing to note about functions, and this goes for all of R, is that there's a function name, in this case, it's abs, there's an open parenthesis, and then inside you'll put in your arguments, the variables of interest, and then a close parentheses. That's the general form of a function. Other functions might have other arguments that you can put in there, but these are usually one number at a time. Okay. So we have the absolute value of five. We can take the log of 5. We can take log of 5, base is equal to 3, if you want to do it that way. Exponent, exp. Square root. Square root of 4 is 2. Factorial of 9 is 362,000 plus. Then, your traditional trig functions, sine of zero, sine of pi. There you have it. So those are your basic functions. I encourage you to look at the R cheat sheet and practice some of these functions on your own. If you don't know what these functions mean, because you've never been exposed to something like, for example, factorial, don't worry about it. Your knowledge will drive what you need to know in terms of the function. So perhaps someday you will come across the need to use the factorial function. Maybe you're doing some combinatorics, and when you're studying that, then this will become useful. That wraps up arithmetic functions in R.