_Application.CalculationVersion property

Returns a number whose rightmost four digits are the minor calculation engine version number, and whose other digits (on the left) are the major version of Microsoft Excel.

Namespace:  Microsoft.Office.Interop.Excel
Assembly:  Microsoft.Office.Interop.Excel (in Microsoft.Office.Interop.Excel.dll)

int CalculationVersion { get; }

Property value

Type: System.Int32

If the workbook was saved in an earlier version of Excel and if the workbook hasn't been fully recalculated, this property returns 0.