A blind-folded man is handed a deck of 52 cards and told that exactly 10 of these cards are facing up.

How can he divide the cards into two piles (possibly of different sizes) with each pile having the same number of cards facing up?

• He pick up the first 10 cards. Let the no. of inverted cards in it be x.He will then invert the deck of 10. Now the no. of inverted cards in the deck of 10 = 10-x [ since the cards which were facing up are now facing down and vice versa] The no. of inverted cards in the remaining deck of 42 cards= 10-x[ since x inverted cards initially contained in the deck of 10 cards] Solved! Your dilemma is at rest.
• 9 years agoHelpfull: Yes(0) No(0)
• divide into 2 which equals to 10 and 42
  turn all 10 cards. regardless what amount facing up in these 10, when you turn it, number of card facing up will be equal to number of card facing up in 42 pile
• 8 years agoHelpfull: Yes(0) No(0)