
theorem Th625:
Sum digits(2960,10) = 17
proof
  thus Sum digits(2960,10) = Sum <%0,6,9%>+Sum <%2%> by Th624,AFINSQ_2:55
  .= Sum <%0,6%> + Sum <%9%> + Sum <%2%> by AFINSQ_2:55
  .= (0 + 6) + Sum <%9%> + Sum <%2%> by AFINSQ_2:54
  .= (0 + 6 + 9) + Sum <%2%> by AFINSQ_2:53
  .= 15 + 2 by AFINSQ_2:53
  .= 17;
end;
