Origin of the Modern Igbo Number System

Entry from the dictionary of the Igbo language centering around the Onicha and Asaba dialects, by British government colonial anthropologists Northcote Thomas, 1914.

Many views and suggestions were put forward and the matter was widely discussed before the war. Two years after the war a consensus was reached and since 1972 a new counting system has been in use. …

Perhaps we might be interested in how Igbo came by the names for the place values [the Igbo Standardisation Committee, headed by F. C. Ogbalu]. It did so without borrowing except from within the rich resources of its many dialects. It specialized the meanings of single non-sentential words in the different dialects, whose meanings for the higher numbers were until then rather vague. Thus:

puku (1,000) was 'uncountable’ in a number of the Central dialects.
nde (1,000,000) was 'uncountable' in a number of the Central dialects where ǹdè was known to be higher in value than puku.
ìjèri (1,000,000,000) represented 'uncountable' in a number of West Niger Igbo dialects.

In the case of nàrị (100) certain Igbo dialects, notably in the Nsukka and Aguleri areas of Anambra State, traditionally had this for 100. So, we adopted it but modified its spelling. As for zero we specialized efu (nothingness) and, in addition, borrowed but Igbonized the words nọọ̀tụ̀ and zirò, as synonyms.

– E. ‘Nọlue Emenanjọ (1985). “Language Engineering in Present-Day Igbo.” “In: West African languages in education: papers from the fifteenth West African Languages Congress.” p. 85.