
theorem Th314:
Sum digits(456,10) = 15
proof
  thus Sum digits(456,10) = Sum <%6,5%>+Sum <%4%> by Th313,AFINSQ_2:55
  .= (6 + 5) + Sum <%4%> by AFINSQ_2:54
  .= 11 + 4 by AFINSQ_2:53
  .= 15;
end;
