# 3 First Operations

In this lesson we learn how to calculate Mathematical expressions, as well as store its results in a R object.

## 3.1 Common Mathematical Expressions

Let’s start by using R as a simple calculator in the console directly. So, type in the top-right panel the following expression:

`[1] 7`

Now, how about other, still very simple, operations?

`[1] 12`

Division

`[1] 0.75`

Exponentiation

`[1] 81`

Square Root

`[1] 13`

Natural logarithm

`[1] 2.302585`

Common logarithm

`[1] 1`

Use round brackets to group operations so that they are carried out first

`[1] 34`

What would happen if the round brackets were omitted?

`[1] 100.6667`

The argument of a function can contain arithmetic operations or mathematical expressions

`[1] 4`

Note that in R, you should only use parenthesis (or round brackets) but not square brackets for expressions in R.

`[1] 19`

Another way to ask for R to evaluate (calculate) an expression or piece of code is to select it, and click on the *Run* button on the right side of the first pane. Or, while selected, press *Ctrl + Enter* on your keyboard. Let’s see if we can reproduce the following expression in the “Source” pane (top-left), if you do it correctly, you should find 0.2193828. \[[ (2^3 - 1) - log(10) ] / (3 + \sqrt{7^3 - 4})\]

Lastly, there are some named objects that R provides you, like the constant \(\pi\) or Month names and letters.

`[1] 3.141593`

```
[1] "Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov"
[12] "Dec"
```

```
[1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q"
[18] "R" "S" "T" "U" "V" "W" "X" "Y" "Z"
```