
theorem Th385:
Sum digits(540,10) = 9
proof
  thus Sum digits(540,10) = Sum <%0,4%>+Sum <%5%> by Th384,AFINSQ_2:55
  .= (0 + 4) + Sum <%5%> by AFINSQ_2:54
  .= 4 + 5 by AFINSQ_2:53
  .= 9;
end;
