
theorem
  881 is prime
proof
  now
    881 = 2*440 + 1; hence not 2 divides 881 by NAT_4:9;
    881 = 3*293 + 2; hence not 3 divides 881 by NAT_4:9;
    881 = 5*176 + 1; hence not 5 divides 881 by NAT_4:9;
    881 = 7*125 + 6; hence not 7 divides 881 by NAT_4:9;
    881 = 11*80 + 1; hence not 11 divides 881 by NAT_4:9;
    881 = 13*67 + 10; hence not 13 divides 881 by NAT_4:9;
    881 = 17*51 + 14; hence not 17 divides 881 by NAT_4:9;
    881 = 19*46 + 7; hence not 19 divides 881 by NAT_4:9;
    881 = 23*38 + 7; hence not 23 divides 881 by NAT_4:9;
    881 = 29*30 + 11; hence not 29 divides 881 by NAT_4:9;
  end;
  then for n being Element of NAT st 1 < n & n*n <= 881 & n is prime
  holds not n divides 881 by XPRIMET1:20;
  hence thesis by NAT_4:14;
end;
