
theorem Th205:
Sum digits(336,10) = 12
proof
  thus Sum digits(336,10) = Sum <%6,3%>+Sum <%3%> by Th204,AFINSQ_2:55
  .= (6 + 3) + Sum <%3%> by AFINSQ_2:54
  .= 9 + 3 by AFINSQ_2:53
  .= 12;
end;
