How can i tell if a yugioh card packet contains rare cards?

please

How can i tell if a yugioh card packet contains rare cards?
The material they use to make the holo cards weighs more, but thats so hard to tell without a scale. But the material is also more dense, so if you squeeze the pack the ones that feel a little thicker with less give, it has a holo. Trust
Reply:u cant it tells you on the pack it says it come with what ever amunt of cards and 1 super rare 10 common or somthing like that
Reply:IF it wieghs more it has a holo