Rounding Numbers in Javascript

In javascript you can manipulate numbers by rounding them to the nearest integer using several functions. Below are some functions along with the explanations:

1. Math.round()

• Purpose: Rounds a number to the nearest integer.
• Behavior: Rounds up if the decimal part is 0.5 or greater, and down if it is less than 0.5.

Example:

Math.round(4.5); // returns 5
Math.round(4.6); // returns 5
Math.round(4.4); // returns 4
Math.round(-4.4); // returns -4

2. Math.ceil()

• Purpose: Rounds a number upwards to the nearest integer.
• Behavior: Always rounds up, regardless of whether the number is positive or negative.

Example:

Math.ceil(4.2); // returns 5
Math.ceil(-4.4); // returns -4
Math.ceil(-7.8); // returns -7

3. Math.floor()

• Purpose: Rounds a number downwards to the nearest integer.
• Behavior: Always rounds down, regardless of whether the number is positive or negative.

Example:

Math.floor(4.7); // returns 4
Math.floor(-4.4); // returns -5
Math.floor(-7.8); // returns -8
Math.floor(7.8); // returns 7

4. Math.trunc()

• Purpose: Truncates (removes) the decimal parts of the number, returning just the integer part.
• Behavior: Simply discards anything after the decimal without rounding.

Example:

Math.trunc(4.7); // returns 4
Math.trunc(-4.4); // returns -4
Math.trunc(-7.8); // returns -7
Math.trunc(7.8); // returns 7

Summary of Behaviour:

Function	Description	Example Input	Output
Math.round	Rounds up to the nearest integer	4.2	5
		-4.2	-4
Math.ceil	Rounds up to the next integer	4.2	5
		-4.2	-4
Math.floor	Rounds a number downwards to the nearest integer	4.2	5
		-4.2	-4
Math.trunc	Truncates (removes) the decimal parts of the number, returning just the integer part.	4.2	5
		-4.2	-4