You can't do it directly, but if you can do without the parens, one way:

Format/Cells/Number/Custom:

[=1000]#,##0,;[-1000]0.###,;#,##0,

Format/Conditional Format:
CF1: Cell value is less than 0
Format1: <font/<red


In article . com,
znelson wrote:

I need to round numbers via a custom format. I'm using:

##,##0,_);[Red](##,##0,)

That gives me exactly what I need as long as the number is 1000 or <
-1000 .. there's a problem when the number is only 3 digits long, eg.
500 or -500 .. in which case it shows up as 0 and (0) respectively.

I need help modifying this format to present 3 or 2 or 1 digit numbers
like this: .5 and (.5) respectively. And the catch is, I only want to
see the decimal point when it's necessary, so 1000 would show up as 1
and not 1.0

Any ideas? I've seen numerous posts about rounding to thousands but
none that address this specific issue. Thanks in advance!