Using the numpad with vim

Create a .vimrc file in your home Directory and add the following lines to it:

imap <Esc>Oq 1
imap <Esc>Or 2
imap <Esc>Os 3
imap <Esc>Ot 4
imap <Esc>Ou 5
imap <Esc>Ov 6
imap <Esc>Ow 7
imap <Esc>Ox 8
imap <Esc>Oy 9
imap <Esc>Op 0
imap <Esc>On .
imap <Esc>OR *
imap <Esc>OQ /
imap <Esc>Ol +
imap <Esc>OS