Low-birthweight i believe.
The answer is 20. Hope it helps.
It is 9*9 21 times so
9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9=
1.09418989e20 is the answer.
Answer (13 of the original arrangements are duplicates now, as
AAAF F F FDDDDCC, AAF F F FDDDDCCA, ..., CAAAF F F FDDDDC
are identical): 900900/13 = 69300.
I might not know the answer to this question but I hope you find one
