Article

# Variables, Data Types, and Mathematical Operators

## Use this article as a reference sheet for JavaScript variables, data types, and mathematical operators.

Use this article as a reference sheet for JavaScript variables, data types, and mathematical operators.

- Variables — The
`var`

keyword indicates the creation of a variable. - Data Types —
`'New York City'`

is a string,`40.7`

is a number, and`true`

is a boolean. - Mathematical Operators — The addition (
`+`

), subtraction (`-`

), multiplication (`*`

), and division (`/`

) characters function as mathematical operators.

var location = 'New York City'; var latitude = 40.7; var inNorthernHemisphere = true;

Each line in the example above begins with the keyword `var`

. The `var`

keyword is used to create a variable. The word that immediately follows `var`

is the name of the variable. The variable’s name should describe the value that it stores (e.g. `location`

).

Variables can store any data type, including:

- String — Any grouping of keyboard characters (letters, spaces, numbers, or symbols) surrounded by single quotes (
`'Hello'`

) or double quotes (`"World!"`

). In the example above, the string`'New York City'`

is saved to the variable`location`

. - Number — Any number, including numbers with decimals:
`4`

,`1516`

,`.002`

,`23.42`

. In the example above, the number`40.7`

is saved to the variable`latitude`

. - Boolean — Either
`true`

or`false`

, with no quotations. In the example above, the variable`inNorthernHemisphere`

is set to`true`

. The sample code below contains examples of mathematical expressions:

var num1 = 4; var num2 = 9; var addNumbers = num1 + num2; // addNumbers equals 13 var subtractNumbers = num2 - num1; // subtractNumbers equals 5 var multiplyNumbers = num1 * num2; // multiplyNumbers equals 36 var divideNumbers = num2 / num1; // divideNumbers equals 2.25

In the example above, the values saved to the variables were calculated using the addition (`+`

), subtraction (`-`

), multiplication (`*`

), and division (`/`

) operators.

Variables always store the final value of the expression on the right side of the equals sign (`=`

).