
theorem Th1014:
Sum digits(1265,10) = 14
proof
  thus Sum digits(1265,10) = Sum <%5,6,2%>+Sum <%1%> by Th1013,AFINSQ_2:55
  .= Sum <%5,6%> + Sum <%2%> + Sum <%1%> by AFINSQ_2:55
  .= (5 + 6) + Sum <%2%> + Sum <%1%> by AFINSQ_2:54
  .= (5 + 6 + 2) + Sum <%1%> by AFINSQ_2:53
  .= 13 + 1 by AFINSQ_2:53
  .= 14;
end;
