
theorem Th1073:
Sum digits(888,10) = 24
proof
  thus Sum digits(888,10) = Sum <%8,8%>+Sum <%8%> by Th1072,AFINSQ_2:55
  .= (8 + 8) + Sum <%8%> by AFINSQ_2:54
  .= 16 + 8 by AFINSQ_2:53
  .= 24;
end;
