thus Sum (digits (3760,10)) = (Sum <%0,6,7%>) + (Sum <%3%>) by Th704, AFINSQ_2:55
.= ((Sum <%0,6%>) + (Sum <%7%>)) + (Sum <%3%>) by AFINSQ_2:55
.= ((0 + 6) + (Sum <%7%>)) + (Sum <%3%>) by AFINSQ_2:54
.= ((0 + 6) + 7) + (Sum <%3%>) by AFINSQ_2:53
.= 13 + 3 by AFINSQ_2:53
.= 16 ; :: thesis: verum