Guide - Counting Suji

Counting suji is a simple way to estimate the danger of any given discard, especially when you have reason to think the opponent has a ryanmen wait. This post will go over how to do it.

As a prerequisite, you should know what suji is. Here's a good guide that includes it. For counting the suji, we need to keep in mind what all the possible suji are. Here's a clip from that article:

Counting suji involves going through all of the opponent's genbutsu, and looking at which suji is accounted for. For example, if you see a 5s in their discards, you know the 2s-5s and 5s-8s suji are covered. These are referred to as "dead suji".

Once you've counted the number of dead suji, you can subtract that number from 18, the number of total suji, to get the number of live suji. For example, if you counted 10 dead suji, then there are 8 live suji. If the opponent has a ryanmen wait, this means that a non-suji 3 would have a 1/8 chance of dealing in. A non-suji 5 would have a 2/8 chance, or a 1/4 chance.

Let's look at a screenshot from a game to practice.

This was posted in the mahjong discord a while ago. This 7p isn't safe and isn't suji against either of the riichis. So, how dangerous is it? Let's look at all the genbutsu for our shimocha first, as they riichi'd earliest.

The easiest way is to count 2 for each 4/5/6 you see, and then count 1 for every other number tile that isn't a suji of those 4/5/6 tiles. If we look just at shimocha's tiles, we count 1 for the 3m, 2 for the 5m, 1 for the 3p, 1 for the 1p, we don't count the 2m because we already counted 5m, count 1 for the 8s, 2 for the 4s, and 1 for the 2s. That's 9 suji down.

Moving on to toimen, we've already counted all the suji except the 4m, which adds 2 more, for 11 total. Kamicha adds the 6s for another 2, and the 9p for one more, and we're at 14. Looking at our own tiles, we pushed the 9m, which removes one final suji and we're at 15 dead suji.

With 15 dead, that means 3 are live. We can look and see that the live suji are 2p-5p, 5p-8p, and 4p-7p, as we can't see any of those. If shimocha has a ryanmen, this 7p we just drew has a 1/3 chance of dealing in. We could also keep tenpai with a 5p cut, but that has a 2/3 chance of dealing in. Ow.

With such a low number of live suji, it also might simply be the case that shimocha doesn't have a ryanmen wait. Around half of riichis are ryanmen, so of course, half are not. In this case, shimocha had a closed wait for 7s. We'll probably talk about how to guess if an opponent has a ryanmen wait later.

For a bit of extra practice, try to count kamicha's suji. Since he just riichi'd, you only need to look at his own tiles. The number of live suji is the same as the minute of this post's timestamp, so check that to confirm your findings. You can go through your own replays and try counting the suji to practice and get faster and faster.

As for how to actually use it, shory (7d) said he started counting suji once someone riichi'd. So, once shimocha called riichi, you would count the current live suji, and keep adding to it as more tiles are discarded. He also said that with a mangan, he would push down to 8 live suji, or even 6 live, and didn't think too hard about defending with most hands until 12 live. When I pushed a non-suji tile with 5 live suji with a mangan hand, Dasuke said it would have been a nice fight if I had a better wait, so that's a factor too, of course. You have to weigh your chance of winning against the risk you take with the discard.

Note again that a non-suji 4/5/6 can deal into two different suji. If you can see neither, it counts as two. So, with 14 live suji, cutting a 5 would be 2/14, or 1/7, and there are effectively only 7 live suji. Thus, it's much more dangerous to push. You can come up with your own guidelines based on how much risk you like to take.

As an added bonus, if you're counting the suji as they come out, you start to get a pretty good idea of the risks the other players are taking, and can know better how hard they're pushing. Especially when you get to higher levels, you might be able to notice when someone has a strong dama hand, and start wanting to defend against both players.

Hopefully this helped! Good luck!