Being integers between 0 and 255, these all can be represented precisely with 8 bits. Scaling these by is the same as dividing by 16, which is the same as shifting the bits 4 places to the right. In this case, scaling is done by inserting a binary point between the first 4 bits and last 4 bits of each number. That happens to equal the predetermined format of this representation. Consequently, since all these numbers do not require more than 8 bits to represent them as integers, no more than 8 bits are required to scale them down and store them in a fixed-point format.