
theorem Th1055:
Sum digits(576,10) = 18
proof
  thus Sum digits(576,10) = Sum <%6,7%>+Sum <%5%> by Th1054,AFINSQ_2:55
  .= (6 + 7) + Sum <%5%> by AFINSQ_2:54
  .= 13 + 5 by AFINSQ_2:53
  .= 18;
end;
