4 Dots

Did you know

• Along with the 8, it is one of only two dots tiles in this set drawn without any red or pink: every coin is blue.
• The reading suu comes from Chinese sì; everyday Japanese says shi or yon. 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 1 and 7: once an opponent has discarded and , a two-sided wait on the 4 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.¹²

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.¹³

Sources

1. Mahjong tiles, Wikipedia
2. 麻雀牌, Wikipedia (Chinese) Chinese
3. 麻雀牌, Wikipedia (Japanese) Japanese