Week 4 ~ "Maths in Japanese" (Math and CS book club)

This is a weekly reading session of the math and CS book club approaching basic topics in mathematics.

We follow the YouTube series “Maths in Japanese”. This one is designed to introduce mathematical terms for basic topics in mathematics, e.g. basic arithmetic terms, basic geometric terms, basic concepts in algebra… The YouTube series offers human written transcripts (subtitles) you can follow along while watching the videos. Each clip is between 5~12 minutes long.

To solidify the introduced terms we will mix in Wikipedia articles that cover a (loosely) related topic. As some of them tend to be quite long it is possible to either split them up or only read parts of them.

Proposed schedule

Dates Material Quizzes
June 30th - July 7th Maths in Japanese - Chapters “Math 1.1 - 1.4” Week 1
July 7th - July 14th 自然数 (Japanese Wikipedia article) Week 2 ~ part 1, Week 2 ~ part 2
July 14th - July 21st Maths in Japanese - Chapters “Math 2.1 - 2.2”
July 21st - July 28th 三角関数 (Japanese Wikipedia article)
July 28th - August 4th Maths in Japanese - Chapters “Math 3.1 - 3.2”
August 4th - August 11th 正規分布⁺ (Japanese Wikipedia article)
August 11th - August 18th Maths in Japanese - Chapters “Math 4.1”
August 18th - August 25th ベクトル空間 (Japanese Wikipedia article)
August 25th - September 1st Bonus: 複素数 (Japanese Wikipedia article)

⁺marked as “citation needed” → I still think it would be a nice fit

This week’s To Dos

  • Wikipedia: Trigonometric function (三角関数)
  • Polling: participation

Vocab items and Grammar points

In the following table we can collect vocabulary items to help each other following the material:

:sparkles: → math or cs related term

order expression reading meaning occurrence comments
order expression reading meaning occurrence comments
余り :sparkles: あまり 割り算の結果 : remainder Maths 1.1
イコール :sparkles: いこーる equality sign​ Maths 1.1
order expression reading meaning occurrence comments
加算 :sparkles: かさん 足し算 Maths 1.1
仮分数 :sparkles: かぶんすう improper fraction Maths 1.3 e.g. 3/2
加法 :sparkles: かほう 足し算 Maths 1.1
奇数 :sparkles: きすう 2で割り切れない数 Maths 1.4
記法 :sparkles: きほう notation 自然数
逆数 :sparkles: ぎゃくすう reciprocal; inverse number; multiplicative inverse​ Maths 1.3
空白 くうはく 何も書いていない白い間 自然数
偶数 :sparkles: ぐうすう 2で割り切れる数 Maths 1.4
減算 :sparkles: げんざん 引き算 Maths 1.1
減法 :sparkles: げんぽう 引き算 Maths 1.1 WK, lvl 19
厳密に げんみつに strictly Math 1.2; 自然数 => 厳密に言えば
order expression reading meaning occurrence comments
:sparkles: 引き算の結果 Maths 1.1
最小公倍数 :sparkles: さいしょうこうばいすう Least common multiple Maths 1.3
四則演算 :sparkles: しそくえんざん basic arithmetic operations​ Maths 1.1
参照 :sparkles: さんしょう browsing (e.g. when selecting a file to upload on a computer); Reference (computer science)​ Maths 1.4
算術の基本定理, ガウスの「算術の基本定理」:sparkles: さんじゅつのきほんていり Fundamental theorem of arithmetic Maths 1.4
真分数 :sparkles: しんぶんすう proper fraction Maths 1.3 e.g. 1/2
若干 じゃっかん to a certain extend Maths 1.2
循環小数 :sparkles: じゅんかんしょうすう repeating decimals Maths 1.2
:sparkles: しょう 割り算の結果 : quotient Maths 1.1
小数 :sparkles: しょうすう decimal, fractual Maths 1.2
焦点 しょうてん focus Maths 1.1 WK, lvl 42
乗算 :sparkles: じょうざん 掛け算 Maths 1.1
乗法 :sparkles: じょうほう 掛け算 Maths 1.1
除算 :sparkles: じょざん 割り算 Maths 1.1
除法 :sparkles: じょほう 割り算 Maths 1.1
数式 :sparkles: すうしき Expression (mathematics)​ Maths 1.3
ずつ ずつ one by one Maths 1.2
:sparkles: せい 0以上 自然数
正数 :sparkles: せいすう integer Maths 1.2
:sparkles: せき 掛け算の結果 Maths 1.1
素数 :sparkles: そすう prime number​ Maths 1.3
order expression reading meaning occurrence comments
帯分数 :sparkles: たいぶんすう mixed fraction; compound number​ Maths 1.3 e.g. 1 1/2
単純 たんじゅん straightforward Maths 1.2 WK, lvl 34
等式 :sparkles: とうしき equation Maths 1.1
ちなみに ちなみに by the way Maths 1.2
order expression reading meaning occurrence comments
において において as for; regarding Maths 1.2; 自然数
除き去る のぞきさる to eliminate Maths 1.3
order expression reading meaning occurrence comments
一桁 ひとけた one digit Maths 1.2
非循環小数 :sparkles: ひじゅんかんしょうすう 対: 循環小数 Maths 1.2
:sparkles: マイナス、零以下 自然数
含む ふくむ to include, to contain Maths 1.3
分子 :sparkles: ぶんし 分数の上の部分 Maths 1.3
分数 :sparkles: ぶんすう fractions Maths 1.2
分母 :sparkles: ぶんぼ 分数の下の部分 Maths 1.3
変換 :sparkles: へんかん transformation Maths 1.3
補足 ほそく supplement, complement Maths 1.1
order expression reading meaning occurrence comments
無限少数 :sparkles: むげんしょうすう 対: 有限少数 Maths 1.2
無理数 :sparkles: むりすう 対: 有理数 Maths 1.2
order expression reading meaning occurrence comments
約分 やくぶん reduction of a fraction (to lowest terms)​ Maths 1.3
有限少数 :sparkles: ゆうげんしょうすう finite decimals Maths 1.2
有理数 :sparkles: ゆうりすう rational numbers Maths 1.2
order expression reading meaning occurrence comments
陸上競技 りくじょうきょうぎ Athletics (sport)​ Maths 1.2
累乗 :sparkles: るいじょう exponentiation 自然数
レース レース race Maths 1.2
order expression reading meaning occurrence comments
:sparkles: 足し算の結果 Maths 1.1

For suggestions on helpful or often used grammar points feel free to list them here:

  • 例 - example

Additional resources


It’s now a wiki!

Math 1.1

Just trying to watch more Japanese content. First few videos are short and seem reasonable.
1.1 was a a little fast but that’s okay.
I instantly forgot everything after watching but I did recognize a few terms like さん and わる
Kind of cool to have math explained in another language.
I’d like to watch the first few videos.

math 1.2

Pretty easy enough.
I’ll remember than comma can also mean decimal


Awesome. Thanks for sharing and welcome to this book club :slight_smile: Hopefully some of the terms introduced in the videos will pop up in the Wikipedia articles as well to help us to internalize them :crossed_fingers:

And it looks like the Crabigator is preparing me for this book club as well… this is one of my newest items on WK:

Thank you so much :yellow_heart:


I like the idea of following along with youtube videos, especially as the content sounds appropriate enough to watch at work during lunch or a break.

The Wikipedia articles look horrendously long and not language learner friendly (although that’s most of Wikipedia), so if sections from the articles aren’t picked, I may only follow the discussion and not directly read them. If only some sections are picked, I’m sure the people who want to read the whole article will do so anyway and comment in the thread too.

Also, regarding the start time, I wonder how many current members of the book club are taking the JLPT? Personally, I’m devoting my non social free time to that, so I’ll probably join about a week late.


Thanks for sharing. Yes, the poll is quite balanced with some people interested in reading the full articles and some in splitting / reading only parts of it. That’s why ~ so far ~ I favor to recommend some sections for those who do not want to read the full articles instead of splitting it in multiple weeks. As you pointed out, with this strategy those who want to read the full article can do this as well.

As for myself, the articles are a little bit above my level so I will only read parts of the Wikipedia articles. …and I’ll try to find those that utilizes some of the terms we’ve encountered in the video clips from the mentioned YouTube series :slight_smile:

That’s a very good point. I’ll take the mock test during the upcoming community event but I totally understand that those who are going for the actual certificate will be super focused the days before the test… and probably want a little bit of rest afterwards :sweat_smile:

Would be cool to have you joining us once you fell ready for new adventures after the JLPT.

math 1.3

Not really sure why I watched this
but I did. I have zero interest in math.
Well actually I’m trying to get off of English content and I don’t really know what to watch yet. Math videos can’t hurt. It all counts.

1 Like

Is someone going to maintain this like a regular book club, with polls and reminders at the start of the week?

1 Like

Thanks for checking-in. Yes, during コンピュータの秘密 book club I was usually checking-in with my own questions / thoughts at the end of the week ~ or beginning of next week depending on RL situation. But of course everyone can join in for the discussion at any time :slight_smile:

We didn’t do any additional polls during the other book club but I am planning to do one after week two to see how reading the first Wikipedia article went for everyone.

Any ideas / suggestions you want to throw in? Absolutely feel encouraged to address them here or directly apply them… e.g. in case you have some polls in mind :grin:


Weekly participation polls are usually nice - they remind people that the new week’s reading is now up for discussion, you get to see how many people are reading along/have fallen behind/stopped reading, and of course clicking things is always fun :smiley:


Something like the following?

Week 1 ~ Are you reading with us?
  • I’m reading along
  • I’ll catch up later
  • I’ll skip this one
  • I’ve dropped it completely
  • Nope, only here for polling :upside_down:

0 voters

Looks like the first week is almost over already. How is everyone doing? Some of you were busy preparing (and taking) the JLPT and some of you are in the middle of some exam period, right? Hope, everything works out well :slight_smile:

This week we had four videos in total so it is a lot of different material to cover. We will have less videos in the upcoming weeks.

In general, I think the videos are very convenient to follow along. So for those of you who are more into extensive than intensive reading or listening this series seems to work pretty well, I think.

Personally, I’m very happy I came across the terms 「Oのくらい」and「つなぐ」which I learned with our previous book club :star_struck:

Next week we will read our first Wikipedia article. I’ll post a proposal for those of us who do not wish to read the full article later / tomorrow depending on your timezone. I think I’ll stick with the ones I made in our home thread but I’d like to properly link them to some of the material we covered during this week.

Last but not least I am thinking about making some short quizzes so you have something more to Poll on. So stay tuned :blush:


I just watched the videos and they’re really well done and to the point, I enjoyed them.
I thought the notation for repeating decimals with a dot on top was interesting, I’ve never seen that. Is it just a Japan thing? Pretty sure they never taught me this in school.

I didn’t really want to commit to this book club so I haven’t been participating in the polls, just stalking, but we’ll see how things go :slight_smile:


Oh, please! I love quizzes.


I live in Canada and I’m pretty sure I was taught this in school so I don’t think it’s just a Japanese thing.


Welcome to week two. Let’s see who will read along this week :slight_smile:

Week 2 ~ Are you reading with us?
  • I’m reading along
  • I’ll catch up later
  • I’ll skip this one
  • I’ve dropped it completely
  • Nope, only here for polling :upside_down:

0 voters

This week we will read about “Natural Numbers”. Everyone who wants to read the full article feel free to do so.

Everyone who only wants to read part of the article feel free to chose something from the following parts:

  • [1] Introduction: here you’ll get a brief introduction to what a natural number is. It relates especially to the video Math 1.4 as it embeds the natural numbers into whole numbers / integers and addresses the “problem” with the number zero.

  • [2] 記法: here you’ll learn different mathematical notations for what is addressed in [1]

  • [3] 特殊な自然数: here you’ll the terms for prime numbers will be revised. Again, this one relates to Math 1.4, I think.

  • [4] 形式的な定義: here you’ll get a mathematical definition on what a natural number is. Some vocabulary terms from Math 1.1 are used and you can practice reading equations. ( → E.g. do you remember the terms for “brackets” :wink: ) You’ll also learn the terms for distribution law or commutative law and others. Some of them we will see again in week eight when we read about vector spaces.

My recommendations:

  • [1] and [2] go very well together. Especially in case you are busy with other book clubs or RL stuff. You can extend it to [1], [2] and [3].

  • [4] Seems to be very nice in case you want to enhance the topics discussed in week 1.

1 Like

Thanks for sharing. There might be different ways to mark repeating decimals. Sometimes you can see a straight line on top of them instead of the dots :slight_smile:

Absolutely feel welcome to go on your own pace. I think, this book clubs works very well to hop on and off on a weekly basis.

…and here is what I came up with so far :blush:

1.「 7*6=42 」は何と読みますか。

  • ななろくよんじゅうに
  • ななろくが よんじゅうに
  • なな タイム ろくは よんじゅうに
  • なな かける ろくは よんじゅうに

0 voters

2.「 \frac{8x - 4y}{12} 」は何と読みますか。

  • はちエクス マイナス よんワイ ぶん じゅうに
  • じゅうに ぶん はちエクス マイナス よんワイ
  • はちエクス ひく よんワイ ぶん じゅうに
  • じゅうに ぶん はちエクス ひく よんワイ

0 voters

3.「 10/3=3 \cdots3 」は何と読みますか。

  • じゅう ぶん さんは さん あまり さん
  • じゅう ぶん さんは さん てんてんてん さん
  • じゅう わる さんは さん あまり さん
  • じゅう わる さんは さん てんてんてん さん

0 voters

  1. 1.8+8.2=10 」は何と読みますか。
  • いちてんはち たす はちてんには じゅう
  • いってんはち たす はってんには じゅう
  • いってんはち プラス はってんには じゅう
  • いってんはち プラス はってんにが じゅう

0 voters

  1. 少数にはなんのものがありますか。
  • 有限少数
  • 無限少数
  • 循環小数
  • 非循環小数

0 voters

  1. 分数の種類を選んでください。
  • 正の整数
  • 負の整数
  • 真分数
  • 仮分数
  • 帯分数

0 voters

  1. 素数を選んでください。
  • 1
  • 2
  • 3
  • 4

0 voters

In the first couple of questions I added some spaces. It’s still messy but I hope with the spaces you have some chance to read along.

I’m usually very good in making mistakes … please don’t be shy and point the out :sweat_smile:

Feel free to discuss the quiz in here but maybe use spoiler tags or

Spoiler alert

hide tags

so others will be warned.


I think that question 2 is missing の after ぶん. Nice quiz otherwise!


Not gonna lie, those videos were pretty challenging and fast for me (probably because I still need to work on my listening skills), but hopefully as we go along I’ll get used to them more (or maybe just put them on 0.75x speed lol).