4th Commander (EDH) and Probability for Deck Construction: Applications of the fraction 1/10.

1/10

1/10 is roughly equal to 10% of 99 cards.  10% of 99 cards is roughly equal to 10 cards.  This is also an extremely useful fraction.  A situation where such a fraction might come in useful is Auras or Equipments.  For example, if you are playing a green deck, it is generally difficult to remove certain cards from play, and you might want to be able to equip a card with something such as deathtouch, such that you can get an opponent’s cards that are blocking your way into their graveyard.

When I play Commander, if I use the fraction 1/10, I find it is generally most useful for a scenario where I might want to get one of a certain kind of card in a game.  For example, if we consider Equipments as 1/10, then you probably won’t have any in your opening hand.  However, you may not need any in your opening hand.  In fact, it is most probable that you won’t see a single Equipment where there are 10 in a deck until the 4^th turn.  On the 4^th turn, you will probably have 10 cards in your hand, and thus 10% of 10 cards is 1 card.