thus Sum (digits (2340,10)) = (Sum <%0,4,3%>) + (Sum <%2%>) by Th562, AFINSQ_2:55
.= ((Sum <%0,4%>) + (Sum <%3%>)) + (Sum <%2%>) by AFINSQ_2:55
.= ((0 + 4) + (Sum <%3%>)) + (Sum <%2%>) by AFINSQ_2:54
.= ((0 + 4) + 3) + (Sum <%2%>) by AFINSQ_2:53
.= 7 + 2 by AFINSQ_2:53
.= 9 ; :: thesis: verum