rua butu = 2 x 4.
9.

trasa = 10 - 1?
10.

sabulu.
One special point to be noticed in this scale is the irregularity that prevails between 7, 8, 9.

The formation of 7 is of the most ordinary kind; 8 is 2 fours--common enough duplication; while 9 appears to be 10 - 1.

All of these modes of compounding are, in their own way, regular; but the irregularity consists in using all three of them in connective numerals in the same system.