Some people avoid use of three, four, or nine notes because the pronunciations of these numbers are similar to those of "惨 (tragedy)," "死 (death)," and "苦 (agony)," respectively.
３＝惨、４＝死、９＝苦など語呂合わせにより禁忌とし、紙幣の数でそれらを避ける人もいる。