ok so a deck has 52 cards
there are 4 suits so there are 4 cards with 8 on them (8 of clubs, hearts, spades, diamonds)
so
probability is
(desired ourcome)/(total possible)
you have 4 chances ouut of 52 for picking a 8 on the first try
on the second try, you have a 3 out of 51 (assuming you picked an 8 first and you didn't replace it)
multiply them since they are dependent on each ohter
4/52 times 3/51=12/2652=1/221
probability is 1/221