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ceil vs floor vs round

Written byPhuoc Nguyen
Category
JavaScript
Created
01 Sep, 2023
JavaScript provides three methods for rounding numbers: `Math.ceil()`, `Math.floor()`, and `Math.round()`. Each of these methods rounds numbers in a unique way. Let's explore them!

Math.ceil()

The `Math.ceil()` method is used to round up a number to the nearest whole integer.
For instance, if you have the number `4.2`, `Math.ceil(4.2)` will return `5`. Similarly, `Math.ceil(-4.2)` will return `-4` because `-4` is the smallest integer that is greater than `-4.2`.

Math.floor()

The `Math.floor()` method is used to round a number down to the nearest whole integer. Here's how it works: If you have the number `4.2`, `Math.floor(4.2)` will return `4`. `Math.floor(-4.2)` will return `-5`, because `-5` is the largest integer that is less than `-4.2`.

Math.round()

The `Math.round()` method helps you round a number to the nearest whole integer. If the number has a fractional part that's less than `0.5`, it's rounded down; if it's `0.5` or greater, it's rounded up.
For example, if you have the number `4.2`, `Math.round(4.2)` will give you `4`. Similarly, `Math.round(4.5)` will give you `5`. While `Math.round(-4.5)` will give you `-4`.

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Phước Nguyễn