
theorem Th246:
Sum digits(306,10) = 9
proof
  thus Sum digits(306,10) = Sum <%6,0%>+Sum <%3%> by Th245,AFINSQ_2:55
  .= (6 + 0) + Sum <%3%> by AFINSQ_2:54
  .= 6 + 3 by AFINSQ_2:53
  .= 9;
end;
