
theorem Th1059:
Sum digits(648,10) = 18
proof
  thus Sum digits(648,10) = Sum <%8,4%>+Sum <%6%> by Th1058,AFINSQ_2:55
  .= (8 + 4) + Sum <%6%> by AFINSQ_2:54
  .= 12 + 6 by AFINSQ_2:53
  .= 18;
end;
