One thing the Android world is not short of is binary calculators but I required one with very specific functionality and behaviour. Hence ByteSplorer, available from Google Play or a direct download here.
ByteSplorer shows how the byte may be interpreted as an unsigned or signed number and its hexadecimal representation.
There are a limited number of functions as well that allow shifting (to demonstrate its effect on the value) and invert all and add 1 keys to allow experimentation with converting numbers to their to complement negative version.
ByteSplorer is at GooglePlay