
theorem Th817:
Sum digits(1166,10) = 14
proof
  thus Sum digits(1166,10) = Sum <%6,6,1%>+Sum <%1%> by Th816,AFINSQ_2:55
  .= Sum <%6,6%> + Sum <%1%> + Sum <%1%> by AFINSQ_2:55
  .= (6 + 6) + Sum <%1%> + Sum <%1%> by AFINSQ_2:54
  .= (6 + 6 + 1) + Sum <%1%> by AFINSQ_2:53
  .= 13 + 1 by AFINSQ_2:53
  .= 14;
end;
