In AD 690, Wu Zetian (624—705), the only Empress Regnant in the history of China, adopted a number of new characters, one of which was 〇. Originally, it was meant to replace the unwieldy character 星 “star”. After the Empress’s death, the new characters fell into disuse. In 1247, Qin Jiushao (ca. 1202—1261) found a new job for 〇. It was introduced as the symbol for zero in his work 數書九章 (Shùshū Jiǔzhāng, “Mathematical Treatise in Nine Sections”). Another hanzi with the same meaning, 零, is mainly used for financial purposes.