How do I preserve leading zeroes in Mac Excel? I'm using Excel (v 14.4.4) on my Mac (10.9.5).  I have opened a CSV file and I wish to save it to an .xls format (Excel 97-2004 Workbook).  I have a column that has 6 digit numbers, some of which begin with a leading zero.  When I save my CSV to XLS, the cells with leading zeroes lose these leading zeroes.  How do I keep them there?
From the Home tab, select the cells you wish to format, and from the format drop-down under Number select Custom. Or, right-click and choose Format Cells, or hit Cmd-1.

This will pop-up a dialog window with the various formatting options.

Again, make sure you're on Custom.

In the Type box type in: 000000

Click Ok.

Alternatively - change the formatting type to text. This will keep whatever you type in the box.