Edit in JSFiddle

var x = 9.656;
var res1 = x.toFixed(0); // 10
var res2 = x.toFixed(2); // 9.66
var res3 = x.toFixed(4); // 9.6560
var res4 = x.toFixed(6); // 9.656000

document.write(res1 + "<br>"); 
document.write(res2 + "<br>"); 
document.write(res3 + "<br>"); 
document.write(res4 + "<br>");