Pantalopus is in a dark cave with a pile of 100 coins. Pakanina (Pantalopus Grandpa) told you that 20 of the coins are heads side up and the rest are tails side up. It's your job to make Pantalopus make two piles of coins that have the same number of heads side up coins. The room is in total darkness and Pantalopus tells you via the device depicted below that each coin feels the same on both sides.
What to do?
No googling of course.