Mental Calisthenics are exercises that you can do by yourself or with a partner. The intent is to exercise different faculties of the brain and induce a meditative state of mind.
(12) is a game for one player. To start the player should arrange 10 to 100 items and write a digit (0 through 9) on each of them. Then the player should rearrange the objects into a random order. Then wait one day, and looking back try to write down the entire sequence from just looking at the objects and the order that they are placed. The player gets one point for every correct guess.
A sample interaction should go like this:
Objects: 148 932 489 302
A: 148 234 429 002
7 points
This game can only be played about once per day, but the objects can be reused. The interval is necessary to forget anything that might have been left over in short term memory. This game is a halfway training game to develop a memory palace, which is something that many memory athletes swear by.