Onion Math

Onion Math (洋葱数学) is a Chinese K-12 online science-tutoring company founded at the end of 2013 by Linfeng Yang (Harvard), Ruochen Zhu (Duke), and Nuo Li, a former technical executive on Innovation Works' "Dianxin OS" project; Yang and Zhu had earlier run the rural-education nonprofit "Sunshine Library" together starting in 2011 . The company grew out of animated middle-school math courses and positioned itself around "unmanned tutoring" — 100% human-machine interactive learning with adaptive video content — which let it price at about 40 RMB per month with near-zero marginal costs . It started charging users in late 2016 and reached scaled revenue in 2017, with early growth driven largely by word of mouth at below-industry acquisition costs .

On funding, per FreeS Fund's deal announcements: FreeS joined the 30M RMB A+ round in early 2015, followed in the 97M RMB B round in 2017, then came a 120M RMB Series C in February 2018 from Legend Capital and Tencent, and a 300M RMB Series D in February 2019 led by Primavera Capital — bringing cumulative funding past 600M RMB . As of the April 2019 reporting, it claimed over 20 million student users and 600,000 teacher users across 150,000 schools, roughly 65% of them in third-tier-and-below cities and rural areas, with a reported 60%+ share of the online K-12 math market . These figures date from 2018–2019; elsewhere's corpus has no more recent coverage of the company.