<?php
$num = 0;
if ($num > 100) echo 'valor muito alto';
else if ($num < 80 && $num > 51) echo 'valor medio';
else if ($num == 50) echo 'valor perfeito';
else if ($num <= 10) echo 'valor muito baixo';
else if ($num == 0) echo'sem valor';
//https://pt.stackoverflow.com/q/39202/101
PD9waHAKJG51bSA9IDA7CmlmICgkbnVtID4gMTAwKSBlY2hvICd2YWxvciBtdWl0byBhbHRvJzsKZWxzZSBpZiAoJG51bSA8IDgwICYmICRudW0gPiA1MSkgZWNobyAndmFsb3IgbWVkaW8nOwplbHNlIGlmICgkbnVtID09IDUwKSBlY2hvICd2YWxvciBwZXJmZWl0byc7CmVsc2UgaWYgKCRudW0gPD0gMTApIGVjaG8gJ3ZhbG9yIG11aXRvIGJhaXhvJzsKZWxzZSBpZiAoJG51bSA9PSAwKSBlY2hvJ3NlbSB2YWxvcic7CgovL2h0dHBzOi8vcHQuc3RhY2tvdmVyZmxvdy5jb20vcS8zOTIwMi8xMDE=