A device which enables fully automatic removal of spot-check samples from unfolded cartons, and predetermines, by means of a counting and marking unit, a precise selected stack quantity from a travelling endless stack disposed in a scale-like configuration, so that they can be combined into a truss at the end of the scale stack. The device comprises a conveyor belt upon which the endless stack is transported in an oblique scale-like configuration at variable speed, a vertically-adjustable hold-down bar defining the stack height, a sensor scanning the stack height, at least one optical measuring arrangement for the position at any moment of a carton, a gripper disposed on a travelling gripper carriage for spot-check sampling, a magazine for receiving the removed spot-check samples and a pusher marking a folded carton.