Chinese Official Mahjong · 64 pt

Pure Terminal Chows in Chinese Official Mahjong (MCR): Points, Rules and Examples

In Chinese Official Mahjong, Pure Terminal Chows (一色双龙会, "one-suit double dragon") is worth 64 points: two 123 chows and two 789 chows of one suit — two pairs of Two Terminal Chows — plus the 5 of the same suit as the pair.

The rules for Pure Terminal Chows

• Four chows: 123, 123, 789, 789 of the same suit
• The pair is the 5 of that suit; any other pair, or a 5 of another suit, does not qualify
• One suit only, no honors
• Chows can be claimed — it does not need to be concealed

What Pure Terminal Chows does not combine with

Under the non-repeat principle these are implied and not counted:

• Full Flush (24) and No Honors (1)
• All Chows (2): four chows and a suit pair
• Seven Pairs (24): 112233 778899 55 can also be read as seven pairs, but Pure Terminal Chows absorbs it
• Pure Double Chow and Two Terminal Chows: none of the 1-point chow combinations between the four chows are scored (once the engine finds Pure Terminal Chows, it scores no further combinations among those chows)

Still counted: Concealed Hand or Fully Concealed Hand, Single Wait, Closed Wait and other win-type fan, plus Self-Drawn.

Scoring examples

Both hands are scored live by the game's own code, including the fan not counted under the non-repeat rule.

The same tiles can also be read as seven pairs (11 22 33 77 88 99 55), but Seven Pairs plus Full Flush is only 48 points. Following "take the higher reading", the engine scores Pure Terminal Chows.

How it relates to other fan

• Three-Suited Terminal Chows: 123 + 789 in two suits with a pair of 5 in the third, 16 points.
• Two Terminal Chows: 123 + 789 of one suit, 1 point; Pure Terminal Chows is two of them plus a 5 pair.
• Full Flush: Pure Terminal Chows is always a Full Flush, so Full Flush is not counted.
• Seven Pairs: the alternative reading of the same tiles, worth less.
• Pure Double Chow: two identical chows, 1 point — not added inside Pure Terminal Chows.

Odds of Pure Terminal Chows

All 14 tiles must be one suit, using only the 1, 2, 3, 5, 7, 8 and 9. The chart shows the largest single-suit count in a 13-tile opening hand:

Source: 1,000,000 random 13-tile deals (flowers already replaced).

Nine or more tiles of one suit at the start happen only about 0.25% of the time. In 4,000 computer-played hands (3,849 wins) Pure Terminal Chows appeared 0 times — far too small a sample for such a specific hand; you will almost never see it.

When to go for it

• It nearly always grows out of a Full Flush: you already hold 123, 789 and a pair of 5 in one suit, and the second set of chows starts to appear.
• Each of 1, 2, 3, 7, 8, 9 is needed twice; three copies of one of them in the discards kills it.
• The fall-backs are excellent: Full Flush alone is 24 points with Two Terminal Chows and Pure Double Chow, or Seven Pairs plus Full Flush.

Try it yourself — play MCR online against the computer, with scoring done for you.

FAQ

How many points is Pure Terminal Chows?

Pure Terminal Chows is worth 64 points in Chinese Official Mahjong. It does not add Full Flush, All Chows, Seven Pairs, Pure Double Chow, Two Terminal Chows or No Honors.

Must the pair be a 5?

Yes, and of the same suit as the chows. With another pair it is a Full Flush with Two Terminal Chows and Pure Double Chow.

Can the chows be claimed?

Yes. Pure Terminal Chows does not need to be concealed; claimed chows count.

What is the difference from Three-Suited Terminal Chows?

Pure Terminal Chows is all one suit, 64 points; Three-Suited Terminal Chows has 123 + 789 in two suits and a pair of 5 in the third, 16 points.

Related fan

Three-Suited Terminal Chows 16 pt Two suits of 1-2-3 + 7-8-9 and a pair of 5s in the third — 16 points. A rigid shape that swallows All Chows and the small chow fan. Two Terminal Chows 1 pt 1-2-3 plus 7-8-9 of one suit for 1 point: when it isn't counted, how account-once limits it, and its link to Outside Hand. Full Flush 24 pt Every tile from a single suit for 24 points. Examples, the non-repeat rules, Half Flush vs Full Flush, and how many suited tiles you need.