This application can be used to score bridge games using Russian IMP scoring. This method uses the high card points (aka HCP: Ace = 4, King = 3, Queen = 2, Jack = 1) of the partnership to determine a score that the partnership should achieve (using normal bridge scoring).
The next step is to take the two scores (the expected score and the achieved score) and compare them. The difference between these scores is used to look up the partnerships final IMP score.
Example: The partnership with the winning bid has 27 points. The expected score is 400 (this is always the case for 27 points). If the bid is 3NTX (3 No Trump Doubled) and it is made with no over tricks, the normal bridge score is 550 (3NT = 40+30+30 = 100, Doubled = 100, Game Bonus = 300, Double Insult = 50). Thus the partnership has made 150 extra points (550[actual] - 400[expected for 27pts]). This 150 is used to look up the IMP score of 4.