
theorem Th29:
Sum digits(70,10) = 7
proof
  thus Sum digits(70,10) = Sum <%0%>+Sum <%7%> by Th28,AFINSQ_2:55
  .= 0 + Sum <%7%> by AFINSQ_2:53
  .= 7 by AFINSQ_2:53;
end;
