How do u tell if a pack of yugioh cards had a super rare or better in it?

i always here people talking about how there is a way to get really rare cards but i cant figure it outany help would be appreciated

How do u tell if a pack of yugioh cards had a super rare or better in it?
The best most reliable way is to scale them. If you go to ebay and buy a pocket scale for around 20 bucks you can use it and scale packs. This is what you do. You take the packs put and weigh each of them individually. You take the heaviest packs and leave the rest. Usually you take about 7-8 of the heaviest packs. This method maybe difficult because the packs maybe be inside a cardboard case like at wal mart. If you have access to a local hobby shop and the owner allows you to scale then you are in luck because it is most accurate that way. Just be sure to thank the owner for allowing you to scale.
Reply:there is no real easy way to tell if you have chosen a pack with a ultra rare card in it... somtimes if u can feel the pack an compare another booster pack u might notice a bit of a thickness in them, chances are that the rarest and most valuable card (u know the ones that are all shiny) those types of cards tend to bend an curve alil, its still hard to tell, i bought a few Jaden Yuki 2 packs an i felt 2 packs an one of them was alil thicker, wen i bought it an chose it i got a Elemental Hero Dark Neos, i wouldnt say i new it was a ultra rare card, but ya it is somtimes easy to tell if u chose a rare card... but still its no sure thing that u got a good pack...