I am seeing some very strange behavior. In the attached workbook, cell B1726 on the Input sheet has formula =B1725. In memory in my C# program, after CalculateFormula is called for the workbook, I can see the DoubleVal…...I inspect the XML for the worksheet, the value for B1726 is 0...double valueB1725 = workbook.Worksheets[0].Cells["B1725"].DoubleValue;...