If you're familiar with how the hidden bit works for IEEE floating point, use a hidden '10' in front of the fraction for negative numbers for posits and suddenly a whole bunch of math falls out. This is equivalent to having the fraction be added to a -2 value which pins the 'overall value' of the fraction to be between -1 and -2, (like how for positive values the hidden bit is 1 and the 'overall value' of the fraction is pinned to between 1 and 2).
