# Math

Updated on Dec 22, 2021 by [Alan Morel](/content/alanmorel/index.html)

## Table of Contents

1. [Arithmetic Operators](/content/classes/javascript/math#arithmetic-operators/index.html)
2. [Math Properties](/content/classes/javascript/math#math-properties/index.html)
3. [Math Methods](/content/classes/javascript/math#math-methods/index.html)
4. [Resources](/content/classes/javascript/math#resources/index.html)

JavaScript makes working with math easy. It provides us with the **arithmetic operators** you'd expect from a programming language and offers us a useful built-in **Math library** that does a lot of work for us so that we can focus on writing great code instead.

Math is easy.

## Arithmetic Operators

Here are some of the many **arithmetic operators** that allow you to manipulate numbers in JavaScript.

### Addition

You can add two numbers together using the `+` operator. For example:

```javascript
const blueCars = 4;
const redCars = 5;

const totalCars = blueCars + redCars;

console.log("I have " + totalCars + " cars!");
```

```html
I have 9 cars!
```

You can add `1` to a number using the **increment** operator. For example:

```javascript
let burritos = 4;
burritos++; // adds 1

console.log("I have " + burritos + " burritos!");
```

```html
I have 5 burritos!
```

You can add an arbitrary number by using **addition assignment**. For example:

```javascript
let books = 10;
books += 20; // adds 20 books

console.log("I have read " + books + " books!");
```

```html
I have read 30 books!
```

### Subtraction

You can subtract two numbers using the `-` operator. For example:

```javascript
const bobsApples = 13;
const stolenApples = 7;

const remainingApples = bobsApples - stolenApples;

console.log("After getting robbed, he was left with " + remainingApples + " apples.");
```

```html
After getting robbed, he was left with 6 apples.
```

You can subtract `1` from a number using the **decrement** operator. For example:

```javascript
let waterBottles = 4;
waterBottles--;

console.log("I am down to " + waterBottles + " water bottles!");
```

```html
I am down to 3 water bottles!
```

You can subtract an arbitrary number by using **subtraction assignment**. For example:

```javascript
let apples = 50;
apples -= 30; // subtracts 30 apples

console.log("I have " + apples + " apples left!");
```

```html
I have 20 apples left!
```

### Multiplication

You can multiply two numbers together using the `*` operator. For example:

```javascript
const tacosPerPerson = 3;
const people = 20;

const tacosNeeded = tacosPerPerson * people;

console.log("We need " + tacosNeeded + " tacos for the party.");
```

```html
We need 60 tacos for the party.
```

You can multiply by an arbitrary number by using **multiplication assignment**. For example:

```javascript
let boxes = 2;
boxes *= 5; // multiplies the value by 5

console.log("I have " + boxes + " boxes left!");
```

```html
I have 10 boxes left!
```

### Division

You can divide two numbers together using the `/` operator. For example:

```javascript
const totalSkittles = 75;
const kids = 5;

const skittlesPerKid = totalSkittles / kids;

console.log("Each kid gets " + skittlesPerKid + " skittles.");
```

```html
Each kid gets 15 skittles.
```

You can divide an arbitrary number by using **division assignment**. For example:

```javascript
let peanuts = 100;
peanuts /= 20; // divides the value by 20

console.log("I have " + peanuts + " peanuts left!");
```

```html
I have 5 peanuts left!
```

### Modulus

You can find the remainder of a division by using the `%` operator. For example:

```javascript
const people = 20;
const peoplePerCar = 6;

const peopleInLastCar = people % peoplePerCar;

console.log("The last car will have " + peopleInLastCar + " people in it.");
```

```html
The last car will have 2 people in it.
```

You can find the remainder of an arbitrary number by using **modulus assignment**. For example:

```javascript
let slices = 45;
slices %= 7; // does modulus 7

console.log("I have " + slices + " slices leftover!");
```

```html
I have 3 slices leftover!
```

### Order of Operations

**Order of Operations**, also known as **PEMDAS**, is at play here, including with the use of parentheses. For example:

```javascript
const x = (5 * 3) + 10 / 2;

console.log("The value of x is " + x + ".");
```

The order of operations is very important because it determines how the numbers are calculated and how the values are displayed. For example, the above expression is evaluated as `(5 * 3) + (10 / 2)` which is `20` because the `*` operator has higher precedence than the `+` operator.

## Math Properties

JavaScript's **Math** library, among other things, gives us access to mathematical properties that are commonly used so that we do not need to implement this ourselves. Let's look at some examples below:

### Euler's Number - Math.E

One of these constants is **Euler's Number**, via `Math.E`.

```javascript
const euler = Math.E;

console.log(euler);
```

```html
2.718281828459045
```

### Pi - Math.PI

**Pi** is the ratio of the circumference of a circle relative to its diameter, and is accessed in JavaScript using `Math.PI`.

```javascript
const pi = Math.PI;

console.log(pi);
```

```html
3.141592653589793
```

## Math Methods

Likewise with properties, JavaScript also implements some commonly used mathematical methods that we can use anytime we want.

### Absolute Value

Getting the absolute value of a number is easy. Simply pass a number to `Math.abs()` and it will return what you expect. For example:

```javascript
const a = 6;
const b = -13;

console.log("Absolute value of a is " + Math.abs(a) + ".");
console.log("Absolute value of b is " + Math.abs(b) + ".");
```

```html
Absolute value of a is 6.
Absolute value of b is 13.
```

### Floor

The **floor** method rounds a number down to the nearest integer. Put a number inside `Math.floor()` and you're good to go. For example:

```javascript
const decimal = 24.942;
const floor = Math.floor(decimal);

console.log("The value of floor is " + floor + ".");
```

```html
The value of floor is 24.
```

### Ceiling

The **ceiling** method rounds a number up to the nearest integer. Put a number inside `Math.ceil()` and you're good to go. For example:

```javascript
const decimal = 13.37;
const ceiling = Math.ceil(decimal);

console.log("The value of ceiling is " + ceiling + ".");
```

```html
The value of ceiling is 14.
```

### Logarithm

You can get the **natural logarithm** of a number using the `Math.log()` method. For example:

```javascript
const number = Math.log(1);

console.log("The value of number is " + number + ".");
```

```html
The value of number is 0.
```

### Maximum

You can get the **maximum** of two numbers using the `Math.max()` method. For example:

```javascript
const number = Math.max(14, 349);

console.log("The value of number is " + number + ".");
```

```html
The value of number is 349.
```

### Minimum

You can get the **minimum** of two numbers using the `Math.min()` method. For example:

```javascript
const number = Math.min(53, 94);

console.log("The value of number is " + number + ".");
```

```html
The value of number is 53.
```

### Power

You can take the **power** of a number by using `Math.pow()`. For example:

```javascript
const number = Math.pow(3, 2);

console.log("The value of number is " + number + ".");
```

```html
The value of number is 9.
```

### Random

To get a **random number** in JavaScript, there's a `Math.random()` method for that. By itself, it just returns a number between `0` and `1`.

```javascript
const random = Math.random();

console.log("The value of random is " + random + ".");
```

```html
The value of random is 0.2156683652500082.
```

However, you can manipulate this fact to get a random number between two other numbers, like this:

```javascript
function randomBetween(min, max) {
    return Math.floor(Math.random() * (max - min + 1)) + min;
}
const random = randomBetween(5, 25);

console.log("The value of random is " + random + ".");
```

```html
The value of random is 15.
```

### Round

You can **round** a number to the nearest integer using `Math.round()`. For example:

```javascript
const rounded = Math.round(3.14159);

console.log("The value of rounded is " + rounded + ".");
```

```html
The value of rounded is 3.
```

### Square Root

You can take the **square root** of a number with `Math.sqrt()`. For example:

```javascript
const root = Math.sqrt(49);

console.log("The value of root is " + root + ".");
```

```html
The value of root is 7.
```

That's all we got for math! 🤓🤓🤓

## Resources

- [Math - MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math)