
theorem Th1240:
Sum digits(3050,10) = 8
proof
  thus Sum digits(3050,10) = Sum <%0,5,0%>+Sum <%3%> by Th1239,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%0%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%0%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 5 + 0) + Sum <%3%> by AFINSQ_2:53
  .= 5 + 3 by AFINSQ_2:53
  .= 8;
end;
