not to overthink

[radosr]

First, you are blindfolded, then given a deck of cards in which 23 of the cards have been flipped up, then inserted into the deck randomly (you know this). You are not allowed to take the blindfold off, however you are asked to split the deck into two stacks such that both stacks have the same number of cards that are flipped up. You are allowed to flip as many cards as you please. How?

 

[Tuan Pham]

how about this: you split the deck into 2 piles: one has 23 cards and the other has 29 cards. Then you flip the pile of 23 cards upside down?