0    = absolutely nothing
 1    = x other
 2    = w other
 4    = r other
 8    = x group
 16   = w group
 32   = r group
 64   = x user
 128  = w user
 256  = r user
 512  = sticky other
 1024 = sticky group
 2048 = sticky user

 add 'em together to get what you want! :)
 e.g.
 umask 384  = rw-------
 umask 448  = rwx------
 umask 457  = rwx--x--x
 umask 420  = rw-r--r--
 umask 4095 = rwsrwsrwt --everything
 umask 4096 = --------- --flips all the bits over