▁is ▁known ▁of ▁his ▁life ▁except ▁that ▁he ▁was ▁a ▁student ▁of ▁Li u ▁Hong , ▁an ▁astronom er ▁and ▁math ematic ian ▁in ▁second ▁century ▁China , ▁and ▁had ▁frequent ▁discuss ions ▁with ▁the ▁Astronom er - Ro yal ▁of ▁the ▁Astronom ical ▁Bureau . ▁ ▁Works ▁▁ ▁X u ▁Y ue ▁wrote ▁a ▁comment ary ▁on ▁N ine ▁Chap ters ▁on ▁Mathemat ical ▁Art ▁and ▁a ▁treat ise , ▁Notes ▁on ▁Trad itions ▁of ▁Ar ithmetic ▁Method s . ▁The ▁comment ary ▁has ▁been ▁lost ▁but ▁his ▁own ▁work ▁has ▁surv ived ▁with ▁a ▁comment ary ▁from ▁Z hen ▁Lu an . ▁ ▁Notes ▁on ▁Trad itions ▁of ▁Ar ithmetic ▁Method s ▁mentions ▁ 1 4 ▁old ▁methods ▁of ▁calculation . ▁This ▁book ▁was ▁a ▁pres cribed ▁mathematical ▁text ▁for ▁the ▁Imperial ▁exam in ations ▁in ▁ 6 5 6 ▁and ▁became ▁one ▁of ▁The ▁Ten ▁Mathemat ical ▁Class ics ▁( 算 经 十 书 ) ▁in ▁ 1 0 8 4 . ▁ ▁References ▁ ▁External ▁links ▁▁▁▁ ▁Category : An cient ▁Chinese ▁mathemat icians ▁Category : Math emat icians ▁from ▁Sh and ong <0x0A> </s> ▁The ▁Z ă pod ie ▁is ▁a ▁right ▁trib ut ary ▁of ▁the ▁river ▁Some ș ul ▁Mic ▁in ▁Roman ia . ▁It ▁dis charg es ▁into ▁the ▁Some ș ul ▁Mic ▁in ▁S ân nico ar ă ▁near ▁Cl uj - N ap oca . ▁Its ▁length ▁is ▁ ▁and ▁its ▁bas in ▁size ▁is ▁. ▁The ▁river ▁was ▁poll uted ▁by ▁the