Maths Puzzle: Coins Solution

QED Gold: Originally uploaded 4th February 2011

Take a random pile of coins. If I tell you how many coins are heads and how many coins are tails, can you separate the pile into two piles with the same number of heads in each. And can you do this with your eyes shut?

Take the same number of coins as there are heads. Call this pile 1. Then;

Total number of coins in pile 1 = Total number of heads

In other words, if h1 and t1 are the number of heads and tails in pile 1, and h2 is the number of heads in pile 2, then;

h1 + t1 = h1 + h2

Cancel h1 on both sides and you will see that the number of tails in pile 1 will be the same as the number of heads in pile 2. So, if you turn over all coins in pile 1 you will now have the same number of heads in each pile.