6 Dots

Did you know

• The red lower half is old: on a Ningbo set from around 1890 the 6 and 7 of dots already have their lower four coins red.¹
• The reading roo comes from Chinese liù; everyday Japanese says roku. Mahjong numbers are read the Chinese way.
• Some Japanese clubs play daisharin ("big wheels"), a local yakuman of the 2 to 8 of dots, two of each. Mahjong Soul rules, and Mahjong Sushi, don't count it.

At the table

• It fits in three sequences, the most any tile can.
• It is suji to the 3 and 9: once an opponent has discarded and , a two-sided wait on the 6 would leave them furiten, which makes it a safer discard against them.
• It is dora when is the dora indicator. Turned up as the indicator itself, it makes dora.

Yaku it can help

• Tanyao simples only
• Chinitsu one suit only
• Chuuren Poutou the nine gates, all in one suit

Where the dots come from

Each dot is a coin: a round copper cash with a square hole, the everyday money of imperial China, straight from the coin suit of the money cards mahjong grew out of. A minority theory has them as the end of a gun barrel instead.²³

Its Chinese names are 筒子 tǒngzi, "barrels", and 餅子 bǐngzi, "cakes". Japanese players first read 筒子 as tonzu; the pinzu they say now survives from the cakes. English speakers call the suit dots, circles or coins.²⁴

Sources

1. 二 一九世紀の中国麻雀牌（プロト・マージャン）, p. 5: ウイルキンソン牌 (the Wilkinson set, Ningbo, c. 1890), Japan Playing Card Museum (日本かるた文化館) Japanese
2. Mahjong tiles, Wikipedia
3. 麻雀牌, Wikipedia (Chinese) Chinese
4. 麻雀牌, Wikipedia (Japanese) Japanese