
theorem Th199:
Sum digits(288,10) = 18
proof
  thus Sum digits(288,10) = Sum <%8,8%>+Sum <%2%> by Th198,AFINSQ_2:55
  .= (8 + 8) + Sum <%2%> by AFINSQ_2:54
  .= 16 + 2 by AFINSQ_2:53
  .= 18;
end;
