
theorem Th296:
Sum digits(171,10) = 9
proof
  thus Sum digits(171,10) = Sum <%1,7%>+Sum <%1%> by Th295,AFINSQ_2:55
  .= (1 + 7) + Sum <%1%> by AFINSQ_2:54
  .= 8 + 1 by AFINSQ_2:53
  .= 9;
end;
