# Javascript: Round up and down to the nearest 5, then find a common denominator

iam looking for a way to Round up AND down to the nearerst 5 and then find a great common denominator of the two numbers. I need it for the caption of a y-skale on a chart.

This is my code so far:

``````function toN5( x ) {
var i = 1;
while( x >= 100 ) {
x/=10;
i*=10;
}
var remainder = x % 5;
var distance_to_5 = (5 - remainder) % 5;
return (x + distance_to_5) * i;
}
``````

The target is something like this: The maximal value (round up to the nearest 5)

``````1379.8 -> 1500
``````

And the other way round - minimal value (round down to the nearest 5)

``````41.8 -> 0
``````

Then i want to find a common denominator like 250 or 500

0 -> 250 -> 500 -> 750 -> 1000 -> 1250 -> 1500

or:

``````0 -> 500 -> 1000 -> 1500
``````

Is ther a way to do something like that? Thanks a lot

If you wanted to round x to the nearest 500, you could divide it by 500, round it to the nearest integer, then multiply it by 500 again:

``````x_rounded = 500 * Math.round(x/500);
``````

To round it to the nearest y, replace 500 with y:

``````x_rounded = 250 * Math.round(x/250);
``````

Hopefully my maths is correct but here are various ways of "rounding"

``````function sigfig(n, sf) {
sf = sf - Math.floor(Math.log(n) / Math.LN10) - 1;
sf = Math.pow(10, sf);
n = Math.round(n * sf);
n = n / sf;
return n;
}

function precision(n, dp) {
dp = Math.pow(10, dp);
n = n * dp;
n = Math.round(n);
n = n / dp;
return n;
}

function nearest(n, v) {
n = n / v;
n = Math.round(n) * v;
return n;
}
``````

demo

Using this api, you can round any number to the nearest multiple of any number, up or down, with this command:

`\$scm.round(number to be rounded).toNearest(multiple to which you want to round);`

For example, if you wanted to round 536 to the nearest 500, you would use:

`\$scm.round(536).toNearest(500);`