# JavaScript Round To Nearest Number

Saturday, April 11, 2009 - 21:47

The JavaScript Math.round() function will round a decimal to the nearest whole number, but I found that I needed was to round a number to the nearest 10. So after a bit of thinking I realised that I could divide the value by 10, round it using the round() function and then multiply the result by 10.

So taking it a step further I decided to create a function that would round a number to the nearest 10, 100, 1000 or whatever value is entered. If this value is less than 0 then do the reverse by multiplying and dividing the number by the given value of accuracy. Here is the function.

 ```1 2 3 4 5 6 7 8 9 10 11 12 13 ``` ```function roundNearest(num, acc){     if ( acc < 0 ) {         num *= acc;         num = Math.round(num);         num /= acc;         return num;     } else {         num /= acc;         num = Math.round(num);         num *= acc;         return num;     } }```

Here are some tests of the function.

 ```1 2 ``` ```alert( roundNearest(12345, 1000) ); // 1200 alert( roundNearest(12345.1234, -100) ); //12345.12```

This function can be simplified a little by putting all of the calculations onto one line.

 ```1 2 3 4 5 6 7 ``` ```function roundNearest(num, acc){     if ( acc < 0 ) {         return Math.round(num*acc)/acc;     } else {         return Math.round(num/acc)*acc;     }  }```
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#### Philip Norton

Phil is the founder and administrator of #! code and is an IT professional working in the North West of the UK.