thus Sum (digits (3340,10)) = (Sum <%0,4,3%>) + (Sum <%3%>) by Th662, AFINSQ_2:55
.= ((Sum <%0,4%>) + (Sum <%3%>)) + (Sum <%3%>) by AFINSQ_2:55
.= ((0 + 4) + (Sum <%3%>)) + (Sum <%3%>) by AFINSQ_2:54
.= ((0 + 4) + 3) + (Sum <%3%>) by AFINSQ_2:53
.= 7 + 3 by AFINSQ_2:53
.= 10 ; :: thesis: verum