if you want to turn it into a function:

var number = 27/7;

// Three decimal places
console.log(round(number, 3));

function round(number, decimal_places)
{
    return Math.round(number * Math.pow(10, decimal_places)) / Math.pow(10, decimal_places);
}

Output:

3.857

Hey I think it’s Math.round(number); and put the number where it says “number”
But here is the link I found it from: https://www.w3schools.com/jsref/jsref_round.asp

Hope this helps!