OpTbl=: _99 ". ];._2 noun define
0 3 1 7 5 9 8 6 4 2
7 0 9 2 1 5 4 8 6 3
4 2 0 6 8 7 1 3 5 9
1 7 5 0 9 8 3 4 2 6
6 1 2 3 0 4 5 9 7 8
3 6 7 4 2 0 9 5 8 1
5 8 6 9 7 2 0 1 3 4
8 9 4 5 3 6 2 0 1 7
9 4 3 8 6 1 7 2 0 5
2 5 8 1 4 3 6 7 9 0
)

getdigits=: 10&#.inv

getDamm=: verb define
  row=. 0
  for_digit. getdigits y do.
    row=. OpTbl {~ <row,digit
  end.
)

checkDamm=: 0 = getDamm