Number format:how I can change the default number format to show blank spaces ?

Does anyone know how I can change the default number format to show blank
spaces rather than commas between thousands. For example:

10 000 000 and (10 000 000) instead of 10,000,000 for positives and
(10,000,000) for negatives. This needs to work such that no matter how big
the number, spaces are put in and not commas.

Also, is it possible to cover circumstances where if there are decimal
points then show them as input:

ie if I type in 5.1 that it shows up as 5.1 where as an input of 5.12 shows
as 5.12 basically depending on how many decimal points are required then
show them.

For all of it, negative numbers to be shown in brackets and in black not
red.

Cheers

Mark.

Use Format Cells
select Number Tab
Select Custom
In the "Type" area, type your format
ie. # ###.###

Unfortunately, what you are trying to do may not be possible.
I tried about 10 or 12 different layouts, and they all failed to one degree or another. The probelem lies in the fact that using a space makes "Excel" think that the cell data is text, not a number as you would expect.

You can simulate your format by putting as many "#" characters as the largest value you expect to be entered.