Hi Ron,

Try using the SUM function on that cell -- it evaluates to zero.

Thanks for pointing out my mistake.
Everything seemed fine when I tried A2 - A1 so I unwittingly assumed
all calculations would be fine. I now see that worksheet functions will
only work with these cells, with the ' prefix, if they are entered as
their value eg SUM(VALUE(A1),VALUE(A2)).
Ken Johnson