
theorem Th234:
Sum digits(119,10) = 11
proof
  thus Sum digits(119,10) = Sum <%9,1%>+Sum <%1%> by Th233,AFINSQ_2:55
  .= (9 + 1) + Sum <%1%> by AFINSQ_2:54
  .= 10 + 1 by AFINSQ_2:53
  .= 11;
end;
