Steps:
a) open new worksheet, set all cells to Number with 4 decimals
b) Set sheet to manual calcs with 1,000 iterations
c) Input the following formulas
I was unable to duplicate this formatting misbehavior with XL2010.
It might be better if you uploaded an example Excel file that duplicates the problem to a file-sharing website, then posting the "shared" URL here.
(I don't believe this forum provides a way to attach the Excel file to a response directly. Other similar forums do provide that feature. That would be preferable, if allowed and I simply overlooked it.)
Some questions:
1. Any chance you can try this with XL2010, XL2007 or XL2003? I have those, but not XL2013.
2. When you say "open new worksheet", do you really mean a new
workbook in a new instance of Excel (as I did)? Or do you have other worksheets with formulas and perhaps some macros?
3. Is it really necessary to set "Enable iterative calculation" with Max Iterations set to 1000 (as I interpreted step #b) in order to duplicate the formatting misbehavior? Your formulas have no circular references.
4. Is it really necessary to set Manual calculation mode in order to duplicate the formatting misbehavior? Presumably you are do that to defer any recalculations until we press F9. But can you duplicate the problem by setting Automatic calculation mode, perhaps pressing ctrl+alt+F9 if necessary?
5. Must the formulas be entered in any particular order to duplicate the formatting misbehavior? I entered all of column D from top to bottom, then E, F and G.
6. G10 could be written more simply: =EXP(G9). Is the form =EXP(1)^G9 necessary to duplicate the formatting misbehavior?
7. For future note, F5 and F6 could be written more simply: =ABS(COS(D5)) and =ABS(COS(D6)). Are the IF() constructs necessary to duplicate the formatting misbehavior?
FYI, I also tried right-clicking on G10 and clicking on Format Cells, then Number tab -- which caused a similar formatting misbehavior for me 2 years ago. That failed to cause any formatting misbehavior in your scenario.