Section 3 Using R as a calculator

To do addition, subtraction, multiplication and division, use the symbols +, -, *, / respectively. For example, if you type 5 * 6 at the command prompt, and press return, you will see

5 * 6

## [1] 30

The symbol ^ is used for raising a number to a power. For example, to calculate \(2^4\), try the following

2 ^ 4

## [1] 16

3.1 Scientific notation

Large numbers may be displayed using “scientific notation”. For example, if we calculate \(500^3\) in R, instead of displaying 125000000 as the result, we see

500 ^ 3 

## [1] 1.25e+08

When you see e appear within a number, read it as “multiplied by 10 to the power of”. So 1.25e+08 is read as “1.25 multiplied by 10 to the power of 8”.

Exercise 3.1 Replace x with a suitable number in the following command

1 / 1000 ^ x

to produce the output

## [1] 1e-09

Check your answer by trying the calculation in R.

3.2 Order of operations

R will follow the BODMAS (Brackets, Orders (powers/roots), Division, Multiplication, Addition, Subtraction) rule for the order in which it will carry out calculations.

Exercise 3.2 First, predict what result you would get from each of these commands. Then try them in R.

4 / 2*2
4 / (2*2)
16 ^ 1/2
16 ^ (1/2)