Microsoft Excel 2019 files have a default extension of ________?

Explanation
List of Microsoft Excel filename extensions Sr# Format Extension 1 Excel Workbook (2007 to 2019) .xlsx 2 Excel Macro-Enabled Workbook (code) .xlsm 3 Excel Binary Workbook .xlsb 4 Template .xltx 5 Template (code) .xltm 6 Excel 97- Excel 2003 Workbook .xls 7 Excel 97- Excel 2003 Template .xlt 8 Microsoft Excel 5.0/95 Workbook .xls 9 XML Spreadsheet 2003 .xml 10 XML Data .xml 11 Excel Add-In .xlam 12 Excel 97-2003 Add-In .xla 13 Excel 4.0 Workbook .xlw 14 Works 6.0-9.0 spreadsheet .xlr