PivotField fieldOrderNo = pivotTable.PivotFields["OrderNo"] as PivotField;
fieldOrderNo.Axis = AxisTypes.Row;
fieldOrderNo.NumberFormat = "0.00";
PivotTable pivottable=sheet2.PivotTables[0];
pivottable.PivotFields[0].NumberFormat = "0.0";
pivottable.PivotFields[1].NumberFormat = "0.00";