When you switch to another language and culture, there are many different things you have to get used to: pronunciation, written script, and customs, among others. But math is one thing that you normally would expect things to be mostly the same, since after all numbers are generally universal, including notation for equations and such.

In Japanese, things like standard numerical notation (i.e. 123) do carry over, although on some documents you can see numbers written with just kanji.

One thing that is a bit peculiar, at least to me, is the “kuku” tables (written in Japanese as 九九, since “ku” is one way to say the number nine). These tables are used for memorization of addition, multiplication, division, and subtraction, but when “九九” is said it usually refers to the single digit multiplication (“掛け算” kakezan) one, which goes up to 9 x 9.

Of course, 2 x 2 = 4 in Japanese, just like it is in English, but the trick with these charts is that there is a special way to pronounce them, which is supposedly to make the flow better (this is called “語呂良く” pronounced “goro yoku”) and facilitate memorization. Lets look at the first few entries of the multiplication 九九 to see what this means:

- 1 x 1 = 1 →
**いん**いち が いち - 1 x 2 = 2 →
**いん**に が に - 1 x 3 = 3 →
**いん**さん が さん

This seems pretty straightforward, except “いん” which is not the normal way to pronounce “1”. However, as you go on there are much more irregularities. For example, here we see the が is omitted:

- 2 x 5 = 10 → に ご じゅう

Any another one, where 3 is pronounced as さぶ instead of さん。

- 3 x 6 = 18 →
**さぶ**ろく じゅうはち

Yet another irregular pronunciation here, this time for “8”. Also 40 is said as しじゅう instead of よんじゅう.

- 5 x 8 = 40 → ご
**は****しじゅう**

You can see the entire chart here.

From what I’ve heard, this method of memorization is used in schools, such as elementary school.

Fortunately, this is something that has little practical use, especially for those who already know our basic math tables. But it is an interesting piece of culture which surprised me when I first learned of it.

Last time I checked the statistics, children in Japan where pretty good in math, at least compared to America which had pretty mediocre scores. I can’t say for certain, but it’s interesting to wonder if these types of learning tricks are somehow related.

**References**

http://ja.wikipedia.org/wiki/九九

http://print-kids.net/print/poster/kakezan-kuku-hyou/kakezan-kuku-hyou1.pdf