Heuristic 4 helps minimize the total amount of information required to memorize the Circle of 4ths/5ths. The Circle of 4ths is 1, 4, b7, b3, b6, b2 , b5, 7, 3, 6, 2, 5, 1. If we ignore the first number after 1, (4) then we see that we have two sets that essentially repeat, but the first set is with flats (bs) before the interval, thus interval set a (b7, b3, b6, b2, b5) set b (7, 3, 6, 2, 5) : Minimizing Total Data for Circle 4th/5ths. Thus utilizing this trick we can eliminate having to know the order of 10 intervals to only 5. So it saves a little space and is an interesting thing the way the interval math works out. Now one might complain this is more trouble than it’s worth and it very well may be, but perhaps if you get it down it helps you really get the Circle of 4ths/5ths into your head.
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