Positioning a set object on a grid

I want objects that are positioned on certain locations to position themselves on a 16*16 grid pattern, after their original position has been set.

Let's say an object is first positioned at 189 pixels (X), i need it to snap to 192 pixels (16*12), the closest number on the grid.

Could anyone help me with this? As soon as math is brought into the picture i find myself at a complete loss.

http://www.clickteam.com/epicenter/ubbthreads.php?ubb=showflat&Board=2&Number=9818

it was... too easy...!

thanks :D