thus Sum (digits (2660,10)) = (Sum <%0,6,6%>) + (Sum <%2%>) by Th594, AFINSQ_2:55
.= ((Sum <%0,6%>) + (Sum <%6%>)) + (Sum <%2%>) by AFINSQ_2:55
.= ((0 + 6) + (Sum <%6%>)) + (Sum <%2%>) by AFINSQ_2:54
.= ((0 + 6) + 6) + (Sum <%2%>) by AFINSQ_2:53
.= 12 + 2 by AFINSQ_2:53
.= 14 ; :: thesis: verum