
theorem Th155:
Sum digits(196,10) = 16
proof
  thus Sum digits(196,10) = Sum <%6,9%>+Sum <%1%> by Th154,AFINSQ_2:55
  .= (6 + 9) + Sum <%1%> by AFINSQ_2:54
  .= 15 + 1 by AFINSQ_2:53
  .= 16;
end;
