
theorem Th759:
Sum digits(396,10) = 18
proof
  thus Sum digits(396,10) = Sum <%6,9%>+Sum <%3%> by Th758,AFINSQ_2:55
  .= (6 + 9) + Sum <%3%> by AFINSQ_2:54
  .= 15 + 3 by AFINSQ_2:53
  .= 18;
end;
