Which number is missing in this barcode?
The barcode consists of 8 rectangles with the respective digits below them. The rectangles 1, 2, 4, and 8 have only one section filled in them. These four single sections are the basics for the combinatorial rectangles: the “3” rectangle is composed of 1 and 2; the “6” one is composed of 2 and 4; and the “5” one is composed of 1 and 4. The “?” rectangle is composed of 1, 2 and 4. Thus, the “?” should be replaced with 7.