'''کیا ابوالحسن کوشیار بن لبّان باشهری گیلانیدیلمی''' (حدود ۹۴۰–۱۰۱۰ میلادی / ۳۳۰–۴۰۰ هجری) [[ریاضیدان]] و [[ستارهشناس]] [[مردم ایرانی]]<ref>{{cite book | last = Hockey | first = Thomas | title = Biographical encyclopedia of astronomers | publisher = Springer | location = New York | year = 2014 | page=1074 | isbn = 978-1-4419-9918-4 |quote=Kushyar ibn Labban was an eminent Iranian astronomer known for his work on astronomical handbooks (zijes) in addition to his work in mathematics and astrology.}}</ref><ref>{{cite book | last = Selin | first = Helaine | title = Encyclopaedia of the history of science, technology, and medicine in non-western cultures | publisher = Springer | location = Berlin New York | year = 2008 | isbn = 978-1-4020-4960-6 | page=241 | accessdate=2 December 2016 | quote=Another important early treatise that publicized decimal numbers was Iranian mathematician and astronomer Kūshyār ibn Labbān’s (fl. 1000) Kitāb fī usūl hisāb al-hind (Principles of Hindu Reckoning), a leading arithmetic textbook.}}</ref> و از اهالی [[گیلان]]ی بود که در پایان قرن چهارم و ابتدای قرن پنجم هجری میزیست.
