
theorem Th336:
Sum digits(665,10) = 17
proof
  thus Sum digits(665,10) = Sum <%5,6%>+Sum <%6%> by Th335,AFINSQ_2:55
  .= (5 + 6) + Sum <%6%> by AFINSQ_2:54
  .= 11 + 6 by AFINSQ_2:53
  .= 17;
end;
