
theorem Th1324:
Sum digits(4325,10) = 14
proof
  thus Sum digits(4325,10) = Sum <%5,2,3%>+Sum <%4%> by Th1323,AFINSQ_2:55
  .= Sum <%5,2%> + Sum <%3%> + Sum <%4%> by AFINSQ_2:55
  .= (5 + 2) + Sum <%3%> + Sum <%4%> by AFINSQ_2:54
  .= (5 + 2 + 3) + Sum <%4%> by AFINSQ_2:53
  .= 10 + 4 by AFINSQ_2:53
  .= 14;
end;
