Rounding Off Numbers

Using Math.round() rounds of a floating point number to a whole number.

If the number after the point is less than 5 it is rounded to the next lowest number.
If the number after the point is 5 or greater it is rounded to the next highest number

Round off 12.34X to 2 decimal places, where X is a number between 1 and 9

Example numbers

num1=12.444
num2=12.545
num3=12.646

toFixed()

Using toFixed(2) gives 2 results depending on the value of X.
If X is less than 5 it is rounded to the next lowest number.
If X is 5 or greater it is rounded to the next highest number

Results based on my example numbers

Math.ceil()

To ensure X is rounded to the next highest number you can use Math.ceil(num*100)/100

Results based on my example numbers

Math.floor()

To ensure X is rounded to the next lowest number you can use Math.floor(num*100)/100

Results based on my example numbers

Rounding Off Numbers2

Enter a long number 
Enter precision     
Result              

<script type="text/javascript">

<!--
function roundOff(value, precision){
value = "" + value //convert value to string
precision = parseInt(precision)

var whole = "" + Math.round(value * Math.pow(10, precision))
var decPoint = whole.length - precision

if(decPoint != 0)
{
result = whole.substring(0, decPoint)
result += "."
result += whole.substring(decPoint, whole.length)
}
else
{
result = whole
}
return result
}
//-->
</script>

<form name=myForm>
<pre>
Enter a long number <input type=text name=text1 value=5.199999999999999999 size=20>
Enter precision <input type=text name=text2 value=2 size=2>
Result <input type=text name=text3>
</pre>
<center>
<input type=button value=Calculate onClick="myForm.text3.value = roundOff(myForm.text1.value, myForm.text2.value)">
</center>
</form>