So some people just hear the words "kung-wen mathematics" (whose Chinese characters imply the word "achievement"), and assume it actually means "document mathematics" (which is also pronounced "kung-wen"). From that they guess that it's probably a mathematics memorization drill class.
有些人只聽到這個名稱，誤把「功文」當「公文」，而顧名思義，猜想這大概是一種死記、背誦式的數學練習法。