Lego goes to great lengths to make its pieces really, really well, says David Robertson, who is working on a book about Lego.

Inside every Lego brick, there are three numbers, which identify exactly which mold the brick came from and what position it was in in that mold. That way, if there’s a bad brick somewhere, the company can go back and fix the mold.

via Why Legos Are So Expensive — And So Popular : Planet Money : NPR.