The phrase "arbitrary number" means a random or chosen number without a specific reason or purpose.
Sentences with «arbitrary number»
Or, you could choose a somewhat arbitrary number of sectors, and a desired allocation based on an arbitrary acceptable «balance» level. (canadiancapitalist.com)
I decided it was worthless to assign arbitrary numbers, and started using numbers that reflected the date the client signed a retainer. (lawyerist.com)