title: How to close-without-save an Excel /xlsm workbook, w/ a custom function, from C#
body: <p>I have an Excel workbook with a custom non-time-dependent cell function that I am opening from a C# WindowsForms application using Interop.Excel. I read four values from it, perform no explicit changes/calculations, then close it from C#.</p>
  
  <p>When I try to directly close (without saving), I get a save prompt. I suspect this is because Excel is interpreting auto-recalculation on open as creating a change, even though nothing actually numerically or formulaically changes. I also set <code>Excel.Application.Calculation = Excel.XlCalculation.xlCalculationManual</code>. How do I prevent the save prompt from appearing and just close-without-save?</p>