
theorem Th1071:
Sum digits(864,10) = 18
proof
  thus Sum digits(864,10) = Sum <%4,6%>+Sum <%8%> by Th1070,AFINSQ_2:55
  .= (4 + 6) + Sum <%8%> by AFINSQ_2:54
  .= 10 + 8 by AFINSQ_2:53
  .= 18;
end;
