XL97: blank cell = 0 ? Why?

[Dianne]

All,

I've been using Excel for years now, but have never noticed this before --
is there some Excel setting I'm overlooking that explains this? Or has it
always worked this way and I've just never clued in till now?

I create a new workbook. In B1, I put the formula:
=IF(A1=0,"Zero","Blank")

Result is "Zero".

If in B1 I put the formula:
=IF(ISBLANK(A1),"Blank","Not blank")

Result is "Blank"

Why would an empty cell = 0?

Thanks for any enlightenment.