
theorem Th393:
Sum digits(620,10) = 8
proof
  thus Sum digits(620,10) = Sum <%0,2%>+Sum <%6%> by Th392,AFINSQ_2:55
  .= (0 + 2) + Sum <%6%> by AFINSQ_2:54
  .= 2 + 6 by AFINSQ_2:53
  .= 8;
end;
