# The difference between JavaScript Math ceil (), floor (), round () three functions

Source: Internet
Author: User
Tags rounds

Here are a few ways to round decimal values to integers: Math.ceil (), Math.floor (), and Math.Round (). These three methods follow the following rounding rules, respectively:
Math.ceil () performs an upward rounding, that is, it always rounds the value up to the nearest integer;
Math.floor () Performs a downward rounding, that is, it always rounds the value down to the nearest integer;
Math.Round () performs a standard rounding, that is, it always rounds a number to the nearest integer (which is also the rounding rule we learned in math Class).

The following are examples of using these methods:

`Alert (Math.ceil (25.9)); 26alert (Math.ceil (25.5)); 26alert (Math.ceil (25.1)); 26alert (Math.Round (25.9)); 26alert (Math.Round (25.5)); 26alert (Math.Round (25.1)); 25alert (Math.floor (25.9)); 25alert (Math.floor (25.5)); 25alert (Math.floor (25.1)); 25`

Nanchang Network Company Technical Staff Summary: for all values between 25 and 26 (excluding 26), Math.ceil () always returns 26 because it performs rounding up. The Math.Round () method returns 26 only if the value is greater than or equal to 25.5, or 25. Finally, Math.floor () returns 25 for all values between 25 and 26 (not including 26).

Ceil (): The fractional part is rounded to the integer part.
Such as:

`Math.ceil (12.2)//Return 13math.ceil (12.7)//return 13math.ceil (12.0)//return 12`

Floor (): All are left, only integers are reserved.
Such as:

`Math.floor (12.2)//Return 12math.floor (12.7)//return 12math.floor (12.0)//return 12`

Round (): Rounding
Such as:

`Math.Round (12.2)//Return 12math.round (12.7)//return 13math.round (12.0)//return 12`

The difference between JavaScript Math ceil (), floor (), round () three functions

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