## Introduction

We all have learned about rounding off numbers in our school. We usually increase the integer if its value is >=.5 and decrease it, if it is <= .4.

1.5 โ 2

1.4 โ 1

We all know JavaScript has a built-in object called Math, which has properties and methods for mathematical constants and functions.

We have three methods that are mostly used to round off a number in JS, i.e., `Math.ceil()`

, `Math.floor()`

, `Math.round()`

. Let's explore them in this article.

## ๐ณ Math.ceil

`Math.ceil`

function in JavaScript is used to round of a number that is passed into it to its nearest integer in upward direction of rounding. What to I mean by upward direction? Towards the greater value. `Math.ceil()`

takes only one parameter that is the value to be rounded. So, if we have a value of 1.4, `Math.ceil()`

will round off it to 2.

```
console.log(Math.ceil(1.4));
//2
console.log(Math.ceil(1.6));
// 2
console.log(Math.round(-1.4));
// 1
console.log(Math.round(-1.6));
// 1
```

*Photo from Wikipedia*

## ๐ณ Math.floor()

Where the `Math.ceil`

method returns the smallest integer greater than or equal to the value we pass, `Math.floor`

returns the largest or equal integer less than the given value. It also takes a single parameter.

*Photo from Wikipedia*

So, if we pass the same value 1.4 in `Math.floor`

, we'll get 1 in return. Even if we pass 1.6, we'll also get 1.

```
console.log(Math.floor(1.4));
// 1
console.log(Math.floor(1.6));
// 1
console.log(Math.floor(-1.4));
// -2
console.log(Math.floor(-1.6));
// -2
```

## ๐ณ Math.round()

`Math.round()`

rounds off the number depending on the fractional part of the number. So, if the fractional part is >=.5, it'll return the smallest integer greater than the passed value and if the number is <=.4 we'll get the largest integer smaller than the number we pass.

```
console.log(Math.round(1.4));
// 1
console.log(Math.round(1.6));
// 2
console.log(Math.round(1.5));
// 2
console.log(Math.round(-1.4));
// -1
console.log(Math.round(-1.6));
// -2
console.log(Math.round(-1.5));
// 2
```

So, Math.round() can go both upward and downward depending on the fractional Part.

## ๐ณ Math.trunc()

There's another method available in JS Math object that is `Math.trunc()`

. `Math.trunc()`

returns the integer part of a number by removing any fractional part of the number.

```
console.log(Math.trunc(1.4));
// 1
console.log(Math.trunc(1.6));
// 1
console.log(Math.trunc(-1.4));
// 1
console.log(Math.trunc(-1.6));
// 1
```

## Conclusion

Rounding off numbers is an essential part of programming. I hope this article revisited your memories about different built-in rounding off methods we have in JavaScript. Leave an โค if you found this article helpful. ๐