There is a large* pile of coins in a room. Almost all of them are turned heads up,
except just 20 which are turned tails up. You know this, but are wearing a blindfold
and gloves (which cannot be removed) so you have no way of telling which are heads
and which are tails.
The challenge: split the coins into two groups, such that both groups have the same number of coins which are tails up. How would you achieve this?
*it can be assumed that there are infinitely many coins.
Hint: the piles do not have to be the same size, which makes sense as the original pile is endless!