
theorem Th70:
Sum digits(88,10) = 16
proof
  thus Sum digits(88,10) = Sum <%8%>+Sum <%8%> by Th69,AFINSQ_2:55
  .= 8 + Sum <%8%> by AFINSQ_2:53
  .= 8+8 by AFINSQ_2:53
  .= 16;
end;
