Oroko counting

One -- e yoko

two -- be be

three -- be dado

four -- be ne

five -- be ta

No problem there.

Five less one -- be ta diyoko

Five less two -- be ta na bebe

Less two -- be be be se

Less one -- e se(e)yoko

Ten -- dondado

Communication linguist [wannabe] that I am, after groaning, "not MORE math in counting!" (think French word for 70, 80 & 90) my first question is "What on earth do they do that makes this kind of distinction useful to them!?" Some things in language happen for no particular reason; however, I do not believe cumbersome methods of counting are one of them. Whatever it was may be long lost, but I'm sure at some point it made sense for these people to use this system of counting and I'm very curious to know why that was.

* first syllable changes with noun class

** <e> <o> <d> substituted for nearest relatives in Oroko alphabet where applicable