Say you have a running count of 21 and to get the true count you must divide the running count by the number of half decks. In this case let's say there are 6 half decks remaining. What is the true count?

In case this is not a clear problem, to use a whole number as the true count, first, choose the closest multiple of 6 to 21. In this case, that could be either 24 or 18.

It would be easiest if the running count was a multiple of the remaining half decks outright. It would be easy to choose the multiple of the remaining half decks that was closest. Yet, there are two multiples of 6 within an equal distance of 21.

What is the best decision or rather, what are the implications of either decision. FYI the true count would either be 4 or 3.

6 = Remaining Half Decks

21 = Running Count

Your time is appreciated. Obviously, the true count you decide affects the plays where deviation may be necessary. Is there a rule of thumb to these situations?