Can someone help explain the parameters of a custom number format?

I want to use this one
_(* #,##0_);_(* (#,##0);_(* "-"??_);_(@_)

But the annoying thing is that it indents the number from the right, meaning
it doesn't fit in my cell properly.
Can someone please tell me how to alter it so that the number remains hard
up against the right edge of the cell?

Thanks in advance
Daniel