Hello,
If your quit date is in cell A1 place this into any other cell:
<TABLE style="WIDTH: 200pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=266><COLGROUP><COL style="WIDTH: 200pt; mso-width-source: userset; mso-width-alt: 4256" width=266><TBODY><TR style="HEIGHT: 15.75pt" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: #eaf1dd; WIDTH: 200pt; HEIGHT: 15.75pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl65 height=21 width=266>=TODAY()-A1</TD></TR></TBODY></TABLE>
You may need to format this cell as number.