
theorem Th633:
Sum digits(3040,10) = 7
proof
  thus Sum digits(3040,10) = Sum <%0,4,0%>+Sum <%3%> by Th632,AFINSQ_2:55
  .= Sum <%0,4%> + Sum <%0%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 4) + Sum <%0%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 4 + 0) + Sum <%3%> by AFINSQ_2:53
  .= 4 + 3 by AFINSQ_2:53
  .= 7;
end;
