The trick is in the corner.

Every card in 3·4·5 has four elements: a color in one corner, a number in another, a letter, and a pictogram. That means every card can be played four different ways depending on what you're building.

You're making designs with three or more cards that share something. A set of one color. A run of numbers in sequence. A word spelled out across letter corners. A matched group of pictograms. Mix and match across your hand to find combinations no one else sees.

To go out, you need three designs played in front of you: one of at least 3 cards, one of at least 4, and one of at least 5. Get there first and the hand ends! The math is simple. The choices aren't.