Excel seems to try and convert text to a value automatically when a mathematical
formula is applied to a cell which contains a text value. The current version of
OOo either ignores the text or treats it as zero.

In the attached sample excel file, the text value "1" in cell A2 is added to the
numerical value 2 in cell A3 and the result displayed in cell A4. In excel the
value in cell A4 is '3'.
 
In OOo 2.4.0 and 2.3.0 (also OOo3devM7) the result is '2' since the text value
in cell A2 is treated as zero. In the ubuntu build of OOo 2.4 (2.4.0-3ubuntu6)
the result in cell A4 is 'Err:529'. If the Value() function is applied to the
value in cell A2 the result is '3' as expected.

This error could be confusing for those switching from excel (I noticed it when
opening an excel file from work which is more detailed than the example - not a
good way to set up a spreadsheet but it works in excel). I think it would be
helpful if OOo was to attempt to automatically apply the value() function to
text, although it is more strictly correct to display the error as in the ubuntu
version.