I said:

Except using field codes, as Jay points out. However, unless you're already
using a field, enshrining your numbers in a { = } field seems like a lot
more work than just adding your own parentheses. It could also be done using
Find/Replace--with or without difficulty depending on whether the numbers
contains commas. Assuming they don't and numbers don't have more than 10
digits, select the table, row, or column of interest, and use:

Find what:-([0-9]{1,10})   (and enable Use wildcards)
Replace with:(\1)

Add the desired currency symbol as needed if you're dealing with money.

You could commit the Find/Replace to a macro and assign it to a
key/button/etc. so that you could simply apply it to a table that's
populated with numbers that need to be ()'ed.

If the numbers contain commas, a more complex specification might be able to
find them, but it's probably not worth the brain strain unless they do.

All in all... I'd use an Excel table if I needed (9) instead of -9 and had a
lot of instances.