If the sum of 19968 and 22235 is expressed as 0063, and the product of 20108 and 19977 as 0362, then how would the difference between 20845 and 20116 be rendered?

unicode 19968(decimal) = (the Chinese character for 1). With the aid of the list of characters posted earlier, this should enable solvers to start decoding the 5-digit codes by substitution.

The 4 digit codes render the precise results of the computations in another system; the puzzle title (see my other earlier clue) provides guidance as to where solvers should start searching for that code.