Hi JTH,
General is just default formatting, where Excel will determine what
you want by looking at what you enter, or how a formula is used
referencing other cells and their formats.
If you change the underlying format between number formats the
change is immediate. But if you change between number and text
or text and number usage then it doesn't really change until reentry.
Adding a null cell constitutes reentry that works for both numbers and for text.
Adding a zero would be valid only for numbers.
F2 then Enter constitutes Reentry but since it is one at a time, it's best use
is for very limited scope of 1 cell, or for testing if that is the problem.
Another way would be with a macro such a byproduct of the
TRIMALL macro used to fix problems such as leading spaces
or use of nonbreaking space characters.
http://www.mvps.org/dmcritchie/excel/join.htm#trimal
which could mess up your data if dates are involved, some
care is required, but it helps with a lot of problems.
Of course this is a different thread than you originally started in the
only beneficiary is you, not a good idea. Best to stick to the
original thread as others mentioned.