
theorem Th224:
Sum digits(34,10) = 7
proof
  thus Sum digits(34,10) = Sum <%4%>+Sum <%3%> by Th223,AFINSQ_2:55
  .= 4 + Sum <%3%> by AFINSQ_2:53
  .= 4+3 by AFINSQ_2:53
  .= 7;
end;
