Ten numbered cards, all face up. Cut anywhere and turn the top two over as a unit, as many times as you like, and watch the two counts below. Then fold the packet: odd positions in one pile, even positions in the other, one pile turned over onto the other — and count the face-up cards.
TopBottom
Ten cards, all face up. Pick a cut and turn the top two over as often as you like.
Odd up
5
Even up
5
Difference
0
No moves yet. Odd positions are 1, 3, 5, 7, 9; even positions are 2, 4, 6, 8, 10.