
theorem Th143:
Sum digits(56,10) = 11
proof
  thus Sum digits(56,10) = Sum <%6%>+Sum <%5%> by Th142,AFINSQ_2:55
  .= 6 + Sum <%5%> by AFINSQ_2:53
  .= 6+5 by AFINSQ_2:53
  .= 11;
end;
