You have a 100 coins laying flat on a table, each with a head side and a tail side. 10 of them are heads up, 90 are tails up. you can’t feel, see or in any other way find out which side is up. split the coins into two piles such that there are the same number of heads in each pile.
so, the solution is take 10 coins off to the side flip those 10 over done
sounds too simple?
this can be solved with algebra for ANY number of coins lets say we have 50 coins, all tails we flip h coins head if h=x+y if we seperate h coins off, we get x heads, and y tails and in the other pile, we have y heads and the rest of the tails so now, if we flip all the coins, we get y heads in the pile and x tails
solution: seperate 10 coins and flip all 10 of them over
