Kazu-ken (ken of numbers), according to history, originated in China, where the oldest version of ken games came from.
In this game, both players make hand gestures with their right hand, representing a number from zero to five. As they do so, they call out the number that is likely to result when the number they had made was added to that of their opponent. The correct number, which is between zero and ten, should be called out in a specially invented language, which sounded similar to Chinese. The left hand, is used to keep a record of the player’s number of wins. In Japan, the loser is forced to drink a cup of sake.
This isn’t the only version. In fact, there is a similar numbers game played with the hands in Italy, called morra, which is believed to go back to ancient Roman times. The Romans called it micatio and were introduced to them by the Greeks. Instead of counting the number of wins with the left hand, the Greeks hold a rod on their left while playing and the position of the hand along with the rod indicate the points or wins of the player.
Though almost all youngsters today are attracted by modern technology, this game is still played, either in schools for entertainment or just for the sake of educating the young ones about culture and tradition in general.