I'm right-handed and use my left hand for mousing. I originally swapped so I wasn't having to move my hand over the number pad to get to and from the keyboard.

I'm right-handed and use my left hand for mousing. I originally swapped so I wasn't having to move my hand over the number pad to get to and from the keyboard. I don't use a keyboard with a number pad any more, but I've stuck with it. It's quick to learn.