
theorem Th106:
Sum digits(39,10) = 12
proof
  thus Sum digits(39,10) = Sum <%9%>+Sum <%3%> by Th105,AFINSQ_2:55
  .= 9 + Sum <%3%> by AFINSQ_2:53
  .= 9+3 by AFINSQ_2:53
  .= 12;
end;
