Cifra mayor de 3 digitos

Warning: Undefined array key "numero" in /home/david/public_html/php/if/tresdigitos/tresdigitos.php on line 21

Warning: Undefined array key "numero" in /home/david/public_html/php/if/tresdigitos/tresdigitos.php on line 22

Warning: Undefined array key "numero" in /home/david/public_html/php/if/tresdigitos/tresdigitos.php on line 23
0-0-0
0 es la cifra mayor