thus Sum (digits (3700,10)) = (Sum <%0,0,7%>) + (Sum <%3%>) by Th698, AFINSQ_2:55
.= ((Sum <%0,0%>) + (Sum <%7%>)) + (Sum <%3%>) by AFINSQ_2:55
.= ((0 + 0) + (Sum <%7%>)) + (Sum <%3%>) by AFINSQ_2:54
.= ((0 + 0) + 7) + (Sum <%3%>) by AFINSQ_2:53
.= 7 + 3 by AFINSQ_2:53
.= 10 ; :: thesis: verum