A low-power display device is provided. The display device is provided with a plurality of display portions. A data driver circuit and an addition circuit are provided to have a region overlapping with the display portion. First analog data is output from the data driver circuit in the case where first digital data consisting of a first digital value is input to the data driver circuit, whereas second analog data is output from the data driver circuit in the case where second digital data consisting of a second digital value is input to the data driver circuit. The addition circuit generates analog data corresponding to digital data that has a high-order bit that is the first digital value and a low-order bit that is the second digital value, by adding the second analog data to the first analog data. An output terminal of the data driver circuit is directly connected to an input terminal of the addition circuit without through an amplifier circuit.