public ExcelRange WriteSumFormulaForRow(int startCol, int endCol, string format = "#,##0.00 ")
{
var startAddr = _ws.Cells[_currentRow, startCol].Address;
var endAddr = _ws.Cells[_currentRow, endCol].Address;
var cell = CurrentCell.WriteSumFormula(startAddr, endAddr, format);
MoveToNextRow();
return(cell);
}