
theorem Th328:
Sum digits(589,10) = 22
proof
  thus Sum digits(589,10) = Sum <%9,8%>+Sum <%5%> by Th327,AFINSQ_2:55
  .= (9 + 8) + Sum <%5%> by AFINSQ_2:54
  .= 17 + 5 by AFINSQ_2:53
  .= 22;
end;
