If I understand you correctly you want the 10 input cell unprotected and
unhidden and the output just protected.

What I do in Excel 2003 is to lock all the cells  in the sheet (Control A,
right click, cell properties, Protection Tab, Locked), then select the 10 cells,
return to the properties and unlock the 10 cells. After you this step, you might
be forgetting to protect the sheet. This will activate the the protection of
cells. (tools/protection/protect sheet). Hide cells is here too, if you don't
want your user to see your formulas.

By default, the individual cells  are protected. Just unprotect the ones you
want unprotected.

But ... by default, the worksheet and workbook are unprotected. Go to Tools
/ Protection (I think, or similar) and protect the workbook and sheet.