
theorem Th348:
Sum digits(779,10) = 23
proof
  thus Sum digits(779,10) = Sum <%9,7%>+Sum <%7%> by Th347,AFINSQ_2:55
  .= (9 + 7) + Sum <%7%> by AFINSQ_2:54
  .= 16 + 7 by AFINSQ_2:53
  .= 23;
end;
