Expressions and Variables

Basic Expressions

Think about what value each of the following expressions will return? Check your answers using the R Console by typing each expression into the console on the line marked > and pressing enter.

  1. 2 - 10
  2. 3 * 5
  3. 9 / 2
  4. 5 - 3 * 2
  5. (5 - 3) * 2
  6. 4 ** 2
  7. 8 / 2 ** 2

Did any of the results surprise you? If so, then might have run in to some order of operations confusion. The order of operators for math in R are the same as for mathematics more generally.

Now turn this set of expressions into a program that you can save by using an R script. For each expression add one line to the script as part of a print statement. Copy and paste the script into the console to display the answer to the screen. If you are using RStudio, you can use Ctrl+Enter (Windows & Linux) or Command+Enter (Mac) to run the line or selection of code directly from your script.

To tell someone reading the code what this section of the code is about, add a comment line that says ‘Exercise 1’ before the code that answers the exercise. Comments in R are added by adding the # sign. Anything after a # sign on the same line is ignored when the program is run. So, the start of your program should look something like:

# Exercise 1
[click here for output]