thus Sum (digits (3025,10)) = (Sum <%5,2,0%>) + (Sum <%3%>) by Th1237, AFINSQ_2:55
.= ((Sum <%5,2%>) + (Sum <%0%>)) + (Sum <%3%>) by AFINSQ_2:55
.= ((5 + 2) + (Sum <%0%>)) + (Sum <%3%>) by AFINSQ_2:54
.= ((5 + 2) + 0) + (Sum <%3%>) by AFINSQ_2:53
.= 7 + 3 by AFINSQ_2:53
.= 10 ; :: thesis: verum