
theorem
  29 is prime
proof
  now
    29 = 2*14 + 1; hence not 2 divides 29 by NAT_4:9;
    29 = 3*9 + 2; hence not 3 divides 29 by NAT_4:9;
    29 = 5*5 + 4; hence not 5 divides 29 by NAT_4:9;
  end;
  then for n being Element of NAT st 1 < n & n*n <= 29 & n is prime
  holds not n divides 29 by XPRIMET1:6;
  hence thesis by NAT_4:14;
end;
