Using R as a Calculator

Order of Operations

When using R as a calculator, the order of operations is the same as you would have learned back in school.

From highest to lowest precedence:

• Parentheses: (, )
• Exponents: ^ or **
• Multiply: *
• Divide: /
• Add: +
• Subtract: -

3 + 5 * 2

[1] 13

Use parentheses to group operations to force the order of evaluation if it differs from the default or to clarify what you intend.

(3 + 5) * 2

[1] 16

This can get unwieldy when not needed but clarifies your intentions. Remember that others may later read your code.

(3 + (5 * (2 ^ 2))) # hard to read
  3 + 5 * 2 ^ 2       # clear, if you remember the rules
  3 + 5 * (2 ^ 2)     # if you forget some rules, this might help

The text after each line of code is called a "comment." Anything that follows after the hash (or octothorpe) symbol # is ignored by R when it executes code.

Really small or large numbers get a scientific notation:

2/10000

[1] 2e-04

Which is shorthand for "multiplied by 10^XX". So 2e-4 is shorthand for 2 * 10^(-4).

You can write numbers in scientific notation too:

5e3  # Note the lack of minus here

[1] 5000