How could I determine the value of a a 1921 Yuan Shikai Chinese silver dollar?
I assume you are speaking of the numismatic value? because if you are not the answer is you weigh the coin and check the value of silver per ounce. Which is often the right answer to this question.
Alternatively you can check ebay and see what other ...
It is evidently a play money banknote that is modeled after the BBk I series in print from 1960–1970 (while the whole design was indeed issued until 1990).
The serial number seems not only to be coloured wrongly, but also has characters all of the same height. This was changed mid-series in 1975: the red numbers would then start with characters ...