google maps api 3 - Try to slightly change geocode of multiple markers on exact same location -

i have similar problem google maps api v3 - multiple markers on exact same spot. have read @ dzinx 's answer , try use it. seems lat , lng cannot use "+". when try "*", worked. datatype of lat , lng float(tried double , decimal also). reason why?

for (var = 0; < locations.length; i++) {   lat = locations[i][0];   lng = locations[i][1]    var marker = new google.maps.marker({position: new google.maps.latlng(lat*2, lng),  icon: 'images/markers_red.png'                 });       markers.push(marker);       marker.setmap(map);      }