Adeck of 52 playing cards, what is the probability of 3 of spades and then a 4 of spades

Well there is only one 3 of spades card in a deck, so the probability of drawing that is 1/52

If you then draw a 4 of spades (if that's the question) that's a 1/51 possibility.

The possibility of choosing randomly a 3rd of spades and then a 4th of spades is 1/52*1/51 or 1/2652.

I hope this answers your question :)