
theorem Th230:
Sum digits(85,10) = 13
proof
  thus Sum digits(85,10) = Sum <%5%>+Sum <%8%> by Th229,AFINSQ_2:55
  .= 5 + Sum <%8%> by AFINSQ_2:53
  .= 5+8 by AFINSQ_2:53
  .= 13;
end;
