
theorem Th286:
Sum digits(76,10) = 13
proof
  thus Sum digits(76,10) = Sum <%6%>+Sum <%7%> by Th285,AFINSQ_2:55
  .= 6 + Sum <%7%> by AFINSQ_2:53
  .= 6+7 by AFINSQ_2:53
  .= 13;
end;
