: digit. ( n -- )
  dup 0= if drop exit then
  dup 1 = if ." one" drop exit then
  dup 2 = if ." two" drop exit then
  dup 3 = if ." three" drop exit then
  dup 4 = if ." four" drop exit then
  dup 5 = if ." five" drop exit then
  dup 6 = if ." six" drop exit then
  dup 7 = if ." seven" drop exit then
  dup 8 = if ." eight" drop exit then
  dup 9 = if ." nine" drop exit then
  dup 10 = if ." ten" drop exit then
  dup 11 = if ." eleven" drop exit then
  dup 12 = if ." twelve" drop exit then
  1 throw
;