thus Sum (digits (2266,10)) = (Sum <%6,6,2%>) + (Sum <%2%>) by Th906, AFINSQ_2:55
.= ((Sum <%6,6%>) + (Sum <%2%>)) + (Sum <%2%>) by AFINSQ_2:55
.= ((6 + 6) + (Sum <%2%>)) + (Sum <%2%>) by AFINSQ_2:54
.= ((6 + 6) + 2) + (Sum <%2%>) by AFINSQ_2:53
.= 14 + 2 by AFINSQ_2:53
.= 16 ; :: thesis: verum