Arithmetic Operators

Learn about the different arithmetic operators and their usage.

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Relation between operators and operands

For numbers, the + and * operators mean the mathematical operations of adding and multiplying two numbers. There are other arithmetic operators. Here’s a full list:

  • +: Addition
  • -: Subtraction
  • *:Multiplication
  • /: Division
  • **: Exponentiation
  • %: Modulo (the signed remainder of a division, for example, 5 % 2 returns 1)

However, some of these operators are also defined on other objects, like strings and arrays.

Try these out:

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puts 2 ** (-3)
puts (-2) ** 3

Operator behavior depends on data types

Recall that some of these operators mean something different for strings. Using a + on two strings simply means that they’ll concatenate into one long string. Using a * between a string and a number repeats it that many times.

We saw something similar for arrays.

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p "ruby" + "!"
p "ruby" * 3
p [1, 2] + [3, 4]
p [1, 2] * 3

Again, the + operator serves to combine two arrays into one big array, while the * operator applied to an array and a number produces a large array with the original elements repeated.