
theorem Th659:
Sum digits(3300,10) = 6
proof
  thus Sum digits(3300,10) = Sum <%0,0,3%>+Sum <%3%> by Th658,AFINSQ_2:55
  .= Sum <%0,0%> + Sum <%3%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 0) + Sum <%3%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 0 + 3) + Sum <%3%> by AFINSQ_2:53
  .= 3 + 3 by AFINSQ_2:53
  .= 6;
end;
