# JavaScript data type: Numbers

JavaScript numbers can be written with or without decimals.

#### Contents

Syntax

Adding

Numeric strings

Number as an object

NaN (Not a number)

## Syntax

Numbers in JavaScript are always 64-bit floating points. There are 2 ways to write a number.

### Style #1: Integer

Integers are whole numbers. They don't contain any period or exponent notation.

```
const x = 10;
```

### Style #2: Floating point aka decimals

Floaters are numbers that contain a period or exponent notation.

```
const x = 0.2 + 0.1; // 0.30000000000000004
```

These types of numbers are never 100% accurate. To solve that problem you will need to do a bit of multiplication and division.

```
const x = (0.2 * 10 + 0.1 * 10) / 10; // 0.3
```

## Adding

You can add two numbers, and it will result to another number.

```
const add = 1 + 4; // 5
```

Be careful! Adding a number type and a numeric string value will result in concatenation.

```
const addWithString = 5 + "10"; // "510"
```

## Numeric strings

JavaScript strings may also contain numeric values, and you can do math operations with them as well.

```
// Subtracting
const a = "10" - "10"; // 0
// Multiply
const b = "10" * "10"; // 100
// Division
const c = "10" / "10" // 1
```

If you pay close attention, I did not include the addition operation. That's because when you use the addition (`+`

) symbol, JavaScript will perform concatenation.

```
const x = "10" + "10"; // 1010
```

## Numbers as objects

Even though JavaScript numbers are usually created from literals. They can also be created as an object.

```
// Type number from literal value
const age1 = 29;
// age2 is now an object instance from new Number()
const age2 = new Number("29");
```

By practice, avoid creating numbers through with the `new Number()`

keywords.

## NaN (Not a number)

`NaN`

is a special keyword in JavaScript that means that a number is not legal.

`NaN`

is usually produce when you execute a mathemetical operation with a non-number value.

```
const y = 5 * "Apples"; // NaN
```

In the code example above I'm doing multiplication with a non-numeric string value, so it results to `NaN`

.

You can find out if a value is a `NaN`

if you use the global JavaScript function `isNan()`

.

```
isNaN(5 / "Apples"); // true
```

`isNaN()`

will return a boolean result.