Bacama language

Bachama (Bachama) is an Afro-Asiatic language spoken in Nigeria in Adamawa State, principally in the Numan Local Government Areas. Dialects are Mulyen, Opalo, and Wa-Duku. Bachama-Yimburu appears to be a closely related but distinct language. Bachama is used as a trade language. It is often considered the same language as Bata.
Numerals.
Bachama has a decimal/quinary number system, with both 5 and 10 as bases:
8 is 4-4, 6 and 7 are based on adding to 5, and 9 means '(10) less 1'.