Table of Contents

## Introduction

Rounding numbers can be a little frustrating if you don’t know the right method or approach to use for it. You might want to round down your number value, and so the static `round`

method would not suffice.

In this article, we will show you two methods that we can use to round down number values in JavaScript.

## Different method to round down in JavaScript

With the built-in `Math`

object, we can carry out many mathematical operations and rounding is one such. The first method that comes to mind when the idea of rounding numbers is present is the `Math.round()`

method.

### Method-1: Using the `round`

method

The `Math.round()`

method rounds its number value argument to the nearest integer based on typical mathematical rounding. So, if the decimal point of the number is greater than or equal to 0.5, it rounds up to the next higher absolute value, but if is lower than 0.5, it rounds down to the lower absolute value. For example, if the number we have is `4.6`

, it will round up to `5`

, but if the number is `4.3`

, it will round down to `4`

.

```
const num = 4.56;
const numRounded = Math.round(num);
console.log(numRounded);
```

Output

```
5
```

However, if we need a case where the decimal point of the number is greater than 0.5 or less than 0.5, it should always round down, we need another method, and that’s where the `floor`

and `trunc`

method comes in.

### Method-2: Using the `floor`

method

The `floor`

method is also a static method within the `Math`

object, and it rounds down the number value passed to it. So, if you pass 4.99 to the `floor`

method, it would return `4`

. Let’s show the `floor`

method in action.

```
const num = 4.98;
const numRounded = Math.floor(num);
console.log(numRounded);
```

Output

```
4
```

With the `Math.floor()`

method, you can round down the number value.

### Method-3: Round down using the `trunc`

method

If you want another static `Math`

method, we make use of the `trunc`

method returns only the integer part of a number (as it removes the decimal number). It works by simply splitting the number from the point of the `dot`

, and return the left side (the integer part).

To illustrate we will use the `Math.trunc()`

method on a whole number and a decimal value.

```
const numOne = 4.98;
const numTwo = 17;
const numOneRound = Math.floor(numOne);
const numTwoRound = Math.floor(numTwo);
console.log(numOneRound, numTwoRound);
```

Output

```
4 17
```

So, with the `4.98`

, it was round down to `4`

, and the number `17`

was left as it is.

## Summary

To round down numbers in JavaScript, we can make use of two static `Math`

method - `floor`

and `trunc`

- which work in different ways but achieve the set goal.

## References

Math.round() - JavaScript | MDN (mozilla.org)

Math.floor() - JavaScript | MDN (mozilla.org)

Math.trunc() - JavaScript | MDN (mozilla.org)