未知数

unknown quantity

not yet / did not / have not / not / 8th earthly branch: 1-3 p.m., 6th solar month (7th July-6th August), year of the Sheep / ancient Chinese compass point: 210°

unknown

to know / to be aware

to count / to count as / to regard as / to enumerate (sb's shortcomings)

number / figure / several / CL:個|个[ge4]

frequently / repeatedly