
theorem Th84:
Sum digits(176,10) = 14
proof
  thus Sum digits(176,10) = Sum <%6,7%>+Sum <%1%> by Th83,AFINSQ_2:55
  .= (6 + 7) + Sum <%1%> by AFINSQ_2:54
  .= 13 + 1 by AFINSQ_2:53
  .= 14;
end;
