
theorem Th1036:
Sum digits(1564,10) = 16
proof
  thus Sum digits(1564,10) = Sum <%4,6,5%>+Sum <%1%> by Th1035,AFINSQ_2:55
  .= Sum <%4,6%> + Sum <%5%> + Sum <%1%> by AFINSQ_2:55
  .= (4 + 6) + Sum <%5%> + Sum <%1%> by AFINSQ_2:54
  .= (4 + 6 + 5) + Sum <%1%> by AFINSQ_2:53
  .= 15 + 1 by AFINSQ_2:53
  .= 16;
end;
