
theorem Th318:
Sum digits(494,10) = 17
proof
  thus Sum digits(494,10) = Sum <%4,9%>+Sum <%4%> by Th317,AFINSQ_2:55
  .= (4 + 9) + Sum <%4%> by AFINSQ_2:54
  .= 13 + 4 by AFINSQ_2:53
  .= 17;
end;
