In the majority of cases, variables will be used in a program to calculate a meaningful result from the user’s input.

In programming, the key arithmetic operators are +, – , * and /.

We will examine another arithmetic operator that is referred to as mod or modulus.

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Operator | Operation | Example |
---|---|---|

+ | Addition | result = 6 + 3 (= 9) |

- | Subtraction | result 6 - 3 (= 3) |

* | Multiplication | result = 6 * 3 (= 18) |

/ | Real Division | result = 6 / 3 (= 2) |

% | Integer Division (Mod) | result = 6 % 3 (= 0) result = 7 % 3 (= 1) |

Note: The integer division (mod) operator calculates and returns the remainder of the calculation with the quotient part being discarded. For example, if the calculation was 5 % 2 this will give a quotient of 2 with a remainder of 1, that is 2 goes into 5 twice but leaves the remainder of 1.

**The Double Life of +**

As well as being used to carry out additions on numeric data the **+** operator can also be used to add strings and characters together. When it is used in this way it is called concatenation, when is basically a fancy word that means joining two things together, for example, the expression FullName = ‘Ada’ + ‘Lovelace’ would assign the value ‘AdaLovelace’ to the FullName variable. If a space is required between the two names it can be added as well, for example, FullName = ‘Charles’ + ‘ ‘ + ‘Babbage’. Which would result in the value of ‘Charles Babbage’.