In The New Standard Orthography the Igbo numerals are based on the metric system. Learning to count in Igbo is as simple as learning to count from One to Ten. This can be done in an amazingly short period of time. With this foundation, it is easy to count in multiples of Ten (Iri), Hundred (Nari), Thousand (Puku), Million (Nde) and Billion (Njeri).
The old orthography is more complex and still in use in most igbo dialects. It is based on multiples of twenty (Ọgụ, Ohu, Oru) and Four hundred (Nnụ). Traditionally all numerals ends at infinity or uncountable (Agụkata agba akwa)