Scoring calculation (Menzen-kafu and Pinfu + more)

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Scoring calculation (Menzen-kafu and Pinfu + more)

Post by Kira » Sun May 09, 2010 1:11 am

I was looking for clarification on Menzen-kafu (the 10fu bonus for winning on discard) and how this particular scoring rule affects pinfu. I presently understand that a 2fu point bonus for tsumo is awarded to an otherwise non-pinfu hand. Is this the same for Kafu and it not being applied to a pinfu? Or is a pinfu only achievable through tsumo?

Hopefuly I have the terms all right hehe.

Thank you~

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Re:Menzen-kafu and Pinfu

Post by Senechal » Sun May 09, 2010 3:06 am

The menzen-kafu points come from any menzen-ron, so pinfu hands are worth 30 and everything else is \"40\" or better after rounding up.

Whereas menzen-tsumo is 1 han rather than 10fu.

Same hand, same tiles: 5200 ron, 7700 tsumo (2000/3900), assuming no extra dora are in play. (Men-tan-dora: 2*34777-567-34588)

With pinfu, same logic. Men-tan-pin (234678-567-34588) is 3han, 30fu as a ron (3900), or 4han, 20fu with tsumo. (5200)
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Re:Menzen-kafu and Pinfu

Post by Kira » Sun May 09, 2010 3:31 am

I understand the pinfu now, but Im having trouble understanding your notation on your examples, so lets see... The attached image is a dealer pinfu won by ron. If this hand was a tsumo, would it be the following?

20fu: futei
(ignore 2fu tsumo)

1han riichi
1han tsumo
1han pinfu
1han dora

7800(2600)

Image

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Re:Menzen-kafu and Pinfu

Post by Senechal » Sun May 09, 2010 12:07 pm

Yes, as you say, it would be 2600 all (7800) because we\'re talking the dealer here.

Both of my other examples are non-dealer totals. You seem to understand perfectly.
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Re:Menzen-kafu and Pinfu

Post by Kira » Sun May 09, 2010 3:17 pm

Hehe thank you. Learning scoring has been kind of daunting, and I don\'t get as much practice with it since the computer does it for me usually.

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Re:Menzen-kafu and Pinfu

Post by azn86.jedi » Tue May 11, 2010 12:57 pm

well i don\'t either, so what i do is look at the hand, look at the score the computer gives, and look at the steps to calculate the fu points to figure out how the computer has come to that score.

counting han is easy enough for me should i recognise the yaku...

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Re:Menzen-kafu and Pinfu

Post by Senechal » Tue May 11, 2010 3:35 pm

If you\'re used to counting stuff or are fast at multiplying, you can either use the solid formula:

FU * 2^HAN * 2^2 * (4 or 6) = total score.
(4 or 6 to represent a non-dealer or a dealer win. Round everything up to the higher 100 of points.)

Or start with what 0 han totals look like then double it from there.

20fu = 320pt
25fu = 400pt
30fu = 480pt
40fu = 640pt
50fu = 800pt

After doubling, say 50fu 3 times: 800 -> 1600 -> 3200 -> 6400... if you are counting a dealer win, then add 50%.

3:50 dealer = 6400 x 1.5 = 9600.

If you\'ve had any inkling of liking math, it is much easier than having to refer to the tables again and again.
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Re:Menzen-kafu and Pinfu

Post by Kira » Tue May 11, 2010 5:36 pm

Hehe I was prepared to remember the static tables, but I\'m wondering if the formula would be easier to memorize. Either way it has to happen, I\'ll be hosting mah-jong games pretty soon.

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Re:Menzen-kafu and Pinfu

Post by Barticle » Tue May 11, 2010 7:54 pm

I\'m of the "let the computer do it for you" school of scoring myself :silly: but a quick note about rounding, Kira.

(Apologies if this is all obvious to you; hopefully someone else out there will find it informative!)
Senechal wrote:FU * 2^HAN * 2^2 * (4 or 6) = total score.
(4 or 6 to represent a non-dealer or a dealer win. Round everything up to the higher 100 of points.)
This is fine for a ron win but with split payments on a tsumo win you need to round up the individual losers\' payments separately.

For example with a non-dealer ron win of 30 fu and 3 han (and the x4 multiplier for non-dealer ron) you get...

30 x 8 x 4 x 4 = 3840 = 3900 rounded up

But with a non-dealer tsumo win with 30 & 3 again the base points are...

30 x 8 x 4 = 960

So two players pay 960 each, rounded up to 1000 each

and the dealer pays 960 x 2 = 1920, rounded up to 2000

which makes 4000 in total.

It\'s interesting to note that this differs from the 3900 above because you rounded before summing the payments. It doesn\'t in all cases, but it does in this example and several others.

Also (as seen in your screenshot, in fact!) a dealer gets 5800 on a 30 & 3 ron win which is slightly less than 3900 + 50% (3900 x 1.5 = 5850), another consequence of rounding early.

(Phew! That was good practice for me - I don\'t do the whole scoring thang very often!)
Kira wrote:Hehe I was prepared to remember the static tables, but I\'m wondering if the formula would be easier to memorize. Either way it has to happen, I\'ll be hosting mah-jong games pretty soon.
I don\'t see any great shame in having score look-up charts (along with a few other reference materials) on your table/s - or at least close to hand - especially if you have learners or less experienced players.

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Re:Menzen-kafu and Pinfu

Post by Shirluban » Tue May 11, 2010 8:09 pm

Thanks Senechal and Barticle for these accurate and clear answers.

I think this thread deserves to be with the \"Spotlights\" ones, so... :)


Edit: I renamed it \"Scoring calculation (Menzen-kafu and Pinfu + more)\", I hope it didn\'t bother you Kira.

By the way, this other thread can be handy too:
http://www.reachmahjong.com/home/index. ... 1709#51717
Cats don't do タンヤオ (tan-yao) but タニャーオ (ta-nya-o).
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Re:Menzen-kafu and Pinfu

Post by Senechal » Tue May 11, 2010 10:33 pm

You can always multiply by [1,1,2] or [2,2,2] to count the partial tsumo payments, or divide the number either given above (3840) or even 3900 into the shares. 975, 975, 1950 still rounds to 1000, 1000 and 2000, giving a total of 4000 for a non-dealer tsumo at 3:30.

EDIT: You mentioned the danger of rounding early. It\'s not so much the rounding early, but the multiplication early before rounding, which was a good point to point out.

3840 -> 3900 x1.5 = 5850 (which would be wrong)
3840 x1.5 = 5760 -> 5800.

You can re-round fractions of a rounded number with the same result, but not multiplying a rounded number.
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Re:Menzen-kafu and Pinfu

Post by Kira » Wed May 12, 2010 1:39 am

Not an issue, Shirluban. I will be trying to remember these formula\'s and the tables I guess! I suppose I can learn them alongside 2000 kanji I intend to learn.

For converting non-dealer tsumo\'s into single point deductions, 50% of the total before bonus will always come from dealer though, right? It\'s not always going to be totally exact, but we are talking about rounding anyways, so.

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Re:Menzen-kafu and Pinfu

Post by Referee » Wed May 12, 2010 1:51 am

It works.

For 7700 hand, half of that: 3850 => 3900 dealer payment
Half of that: 1950 => 2000 children payment.

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Re:Menzen-kafu and Pinfu

Post by Barticle » Wed May 12, 2010 11:12 am

Senechal wrote:3840 -> 3900 x1.5 = 5850 (which would be wrong)
Rounding early (before multiplying)
3840 x1.5 = 5760 -> 5800.
...and rounding late. :)

Although I can\'t really speak from experience, I wonder if the mental arithmatic is any easier if you think in classical terms of doubling - double twice for the bazoro (auto two han for winning) and then double again for each han from yaku and dora.

BTW there\'s a very comprehensive article about scoring in Japanese MJ on English Wikipedia which helped me a lot when I was learning and seems to have been expanded since.

http://en.wikipedia.org/wiki/Japanese_M ... ring_rules

Also a top tip is to play with as many red fives as possible. Playing with more dora means you\'ll hit the mangan limit more frequently and therefore won\'t have to calculate the score so often! :laugh:

Similarly you could also play with the mangan kiriage rule where hands with either 4 han and 30 fu or 3 han and 60 fu are treated as mangan (since their scores come out so close to it already).
Kira wrote:I suppose I can learn them alongside 2000 kanji I intend to learn.
You have my respect - I\'m still struggling with all the kana!

To be fair though I hadn\'t made any serious efforts to learn them all until recently. I\'ve just started using My Japanese Coach for the Nintendo DS which is very good (and very cheap). You can practise reading, writing, speaking and listening comprehension and it has approximately 1000 individual lessons built in! B)

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Re:Menzen-kafu and Pinfu

Post by Kira » Wed May 12, 2010 1:21 pm

The Wikipedia article is great! I think between that and the yaku list I\'ve managed to understand most of the complexities from there. There has only been a couple times when I didn\'t find what I needed and I\'ve had to browse the Japanese Wiki mahjong pages, but that\'s usually to look up words.

Hiragana is okay. Katakana is a pain because of the similar looking characters. I started learning back in high school though, and while I took a break from studying up until about 6 months ago, I managed to still remember my hiragana pretty well. I\'ve seen that \'game\' for DS at the Japanese meetup\'s I attend. Besides a selection of mahjong games, I should pick it up! First though I will probably try to barter with a mahjong table dealer from New Jersey, hehe.

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