Hi,

To reproduce the bug:

* open a new gnumeric sheet
* type a number e.g. 215.31 into A1
* reduce the visible number of significant digits in A1 so that 215 now appears in A1. I used the toolbar button for this.
* Modify the value to 215 in A1 by selecting the cell (double-click) or by using the formula text area i.e. delete ".31".
* Confirm the deletion by pressing Enter.
* value in A1 remains as 215.31 (double-click cell or in formula text area).

To modify the number requires adding the requisite number of significant digits back (using the toolbar button, for example), then deleting the digits as described above.  

This is somewhat related to another bug I recently submitted:

https://bugzilla.gnome.org/show_bug.cgi?id=670550

Thanks.

Vince