Seems like you want the remainder after a division. See http://www.filemaker.com/help/12/fmp/html/func_ref3.33.35.html for that.
If you want you can divide that further.
Filemaker doesn't do fancy stuff like float, longs or doubles, just numbers. So its possible to divide 5 by 7 and get the result you want, just make the field in the layout big enough to show ",714285714" or it will just display a "?"