(open in Excel → Save As .xls )
Select your ID column, right-click, choose Format Cells , and select Text . Do this before typing or pasting any data. ids.xls download
Once you have verified the file is safe and legitimate, immediately use Excel to Save As and convert it to .xlsx (or .xlsb ). This removes the old binary format and strips out embedded macros, reducing future risk. (open in Excel → Save As