The fourth of Fb is bbb and has nine flats (two double flats, bbb and ebb):—
Bbb cb db ebb fb gb ab Bbb
1 2 3∼ 4 5 6 7∼ 8
The fourth of Bbb is ebb and has ten flats (three double flats, bbb, ebb and abb):—
Ebb fb gb abb bbb cb db Ebb
1 2 3∼4 5 6 7 ∼ 8
The fourth of Ebb is abb and has eleven flats (four double flats, bbb, ebb, abb and dbb):—
Abb bbb cb dbb ebb fb gb Abb
1 2 3∼ 4 5 6 7∼ 8
The fourth of Abb is dbb and has twelve flats (five double flats, bbb, ebb, abb, dbb, and gbb):—
Dbb ebb fb gbb abb bbb, cb Dbb
1 2 3∼4 5 6 7 ∼ 8
Dbb has taken us back to our starting key called by a different name as was the case when we had twelve sharps. To continue counting four would take us over the same keys called by different names. As was advised in the sharp keys, this research should be continued by the student. If more than fourteen flats are considered, it will be necessary to add triple flats.