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. How would you split the coins into two piles such that there are the same number of heads in each pile? A babysitter came over to babysit 10 children. She decided to give them a snack. In a jar there are 10 cookies. She wants to give each child a cookie, but still keep one in the jar. How will she do it without breaking any cookie (i.e. each child has to get a whole cookie)?