
theorem Th275:
Sum digits(108,10) = 9
proof
  thus Sum digits(108,10) = Sum <%8,0%>+Sum <%1%> by Th274,AFINSQ_2:55
  .= (8 + 0) + Sum <%1%> by AFINSQ_2:54
  .= 8 + 1 by AFINSQ_2:53
  .= 9;
end;
