**Author:**
MDBootstrap

JavaScript Arithmetic Operators

Arithmetic operators perform arithmetic on numbers (literals or variables).

Operator | Description |
---|---|

+ | Addition |

- | Subtraction |

* | Multiplication |

** | Exponentiation (ES6) |

/ | Division |

% | Modulus (Remainder) |

++ | Increment |

-- | Decrement |

Arithmetic Operations

A typical arithmetic operation operates on two numbers.

The two numbers can be literals:

```
var x = 100 + 50;
```

or variables:

```
var x = a + b;
```

or expressions:

```
var x = (100 + 50) * a;
```

Operators and Operands

The numbers (in an arithmetic operation) are called **operands**.

The operation (to be performed between the two operands) is defined by an **operator**.

Operand | Operator | Operand |
---|---|---|

100 | + | 50 |

Adding

The **addition** operator (`+`

) adds numbers:

```
var x = 5;
var y = 2;
var z = x + y; // Result 7
```

Subtracting

The **subtraction** operator (`-`

) subtracts numbers.

```
var x = 5;
var y = 2;
var z = x - y; // Result 3
```

Multiplying

The **multiplication** operator (`*`

) multiplies numbers.

```
var x = 5;
var y = 2;
var z = x * y; // Result 10
```

Dividing

The **division** operator (`/`

) divides numbers.

```
var x = 5;
var y = 2;
var z = x / y; // Result 2.5
```

Remainder

The **modulus** operator (`%`

) returns the division remainder.

```
var x = 5;
var y = 2;
var z = x % y; // Result 1
```

In arithmetic, the division of two integers produces a **quotient** and a **remainder**.

In mathematics, the result of a **modulo operation** is the **remainder** of an
arithmetic division.

Incrementing

The **increment** operator (`++`

) increments numbers.

```
var x = 5;
x++; // This will increase the value of x by 1
var z = x; // Result 6
```

Decrementing

The **decrement** operator (`--`

) decrements numbers.

```
var x = 5;
x--; // This will decrease the value of x by 1
var z = x; // Result 4
```

Exponentiation

The **exponentiation** operator (`**`

) raises the first operand to the power of
the second operand.

```
var x = 5;
var z = x ** 2; // Result 25
```

x ** y produces the same result as `Math.pow(x,y)`

:

```
var x = 5;
var z = Math.pow(x,2); // Result 25
```

Operator Precedence

Operator precedence describes the order in which operations are performed in an arithmetic expression.

```
var x = 100 + 50 * 3; // Result 250
```

Is the result of example above the same as 150 * 3, or is it the same as 100 + 150?

Is the addition or the multiplication done first?

**As in traditional school mathematics, the multiplication is done first.**

Multiplication (`*`

) and division (`/`

) have higher **precedence** than
addition (`+`

) and subtraction (`-`

).

And (as in school mathematics) the precedence can be changed by using parentheses:

```
var x = (100 + 50) * 3; // Result 450
```

When using parentheses, the operations inside the parentheses are computed first.

When many operations have the same precedence (like addition and subtraction), they are computed from left to right:

```
var x = 100 + 50 - 3; // Result 147
```

Exercises - test your knowledge

Exercise 1

Multiply `10`

with `5`

, and alert the result:

```
alert(10 * 5);
```

Exercise 2

Divide `10`

by `2`

, and alert the result:

```
alert(10 / 2);
```

Exercise 3

Alert the **remainder** when `15`

is divided by `9`

.

```
alert (15 % 9);
```

Exercise 4

`x = 10;`

`y = 5`

Use the correct **assignment operator** that will result in `x`

being `15`

(same as `x = x + y`

).

```
x = 10;
y = 5;
x += y;
```

Exercise 5

`x = 10;`

`y = 5`

Use the correct **assignment operator** that will result in `x`

being `50`

(same as `x = x * y`

).

```
x = 10;
y = 5;
x *= y
```

Previous lesson Next lesson

Spread the word: