For this talk, I will present verbal number in Kibiri [prm], a critically endangered language spoken by 32 people at Kikori and surrounding villages in the Gulf Province of Papua New Guinea. Following Corbett (2000)’s definition of event and participant number, I consider that a language exhibits event number when there is a formal means to distinguish an event being performed one time from several times. Participant number occurs when there is a formal means to distinguish the number of entities involved in the event. Kibiri exhibits both event and participant number with almost the same formal means and on an ergative basis: suppletion and partial reduplication, which leads to a certain level of ambiguity. I suggest a way of disambiguating situations with the four parameters: Once one by one (O1B1), Once at the same time (OATST), Many times one by one (MT1B1), and Many times at the same time (MTATST) which so far have been useful. The methodology is based entirely on empirical data through elicitation (creating and using stimuli videos in the field), recording of oral texts and data discussion with the speakers. A total of 727 videos were shown to 2 speakers and a little less to another speaker. Among the results I can say that Kibiri's verbal number goes along the lines of the typology presented by Cobett (2000); participant number's morphology is more complex than that of event number; and in intransitive dynamic verbs when the participant number of S is SG, partial reduplication expresses event number many times), but when the participant number of S is PL, then partial reduplication expresses plurality of the S participant and event number expression is obliterated