
theorem Th769:
Sum digits(550,10) = 10
proof
  thus Sum digits(550,10) = Sum <%0,5%>+Sum <%5%> by Th768,AFINSQ_2:55
  .= (0 + 5) + Sum <%5%> by AFINSQ_2:54
  .= 5 + 5 by AFINSQ_2:53
  .= 10;
end;
