
theorem Th104:
Sum digits(26,10) = 8
proof
  thus Sum digits(26,10) = Sum <%6%>+Sum <%2%> by Th103,AFINSQ_2:55
  .= 6 + Sum <%2%> by AFINSQ_2:53
  .= 6+2 by AFINSQ_2:53
  .= 8;
end;
