![Enjoy Mathematics from Unsolved Problems - Examples of 3x+1 problems, perfect numbers, etc. (Gijutsu Hyoronsha) [E-book]](https://image.yodobashi.com/product/100/000/086/601/178/094/100000086601178094_10203.jpg)
Enjoy Mathematics from Unsolved Problems - Examples of 3x+1 problems, perfect numbers, etc. (Gijutsu Hyoronsha) [E-book]
Price as listed by the Japanese store — service fee and shipping not included
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Product details
数学上の未解決問題を題材に数学を楽しんでみませんか。未解決問題としてリーマン予想やabc予想，P≠NP予想などが有名ですが，あまり有名ではないけれども解けそうで解けない未解決問題や考え始めると意外と面白い問題が数多く存在します。奇数の完全数は存在するのか（偶数の完全数は存在する），どんな自然数もある操作を繰り返すと1になるというのは本当か？（3x＋1問題）などです。 本書はなぜ未解決なのか，解ける可能性はあるのか，その場合のアプローチは何かも併せて考えていきます。さまざまなタイプの未解決問題を考えることは現代数学の現状と未来を知ることにつながります。
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- Store
- Yodobashi
- Seller
- Yodobashi
- Item code
- 100000086601178094
Weight & dimensions
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* Estimate — final cost is by actual weight at our Japan warehouse.
🚚 Shipping calculator (Japan → Thailand)
🚢 Sea
฿150
By the kilo · 150฿/kg
18-25 days
✈️ Air
฿700
700฿/kg
5-7 days
This is the Japan → Thailand rate and already includes KEX Express home delivery (1-2 more days)
* Estimate — final cost is by actual weight at our Japan warehouse.
Shipping information
Air
5-7 days
Departs daily (closed Sun / JP holidays)
Sea
18-25 days
Cutoff every Fri · ship departs Sat
After clearing Thai customs, delivered to your door by KEX Express in 1-2 days
⚠️ Some items can't ship by air (matcha/tea, high-value brands, pressurized goods) — ask before ordering.
📦 Full shipping rates (Japan → Thailand)View all
✈️ Air Cargo
| Product type | Price |
|---|---|
| General goods | 700 ฿/kg |
| Shoes (boxed) / streetwear / card games | 750 ฿/kg |
| Tennis/badminton rackets, sports gear | 850 ฿/kg |
Minimum weight by box size (W+L+H over 100cm)
| Combined size | Minimum |
|---|---|
| 100 cm | 5 kg |
| 120 cm | 10 kg |
| 140 cm | 15 kg |
| 160 cm | 20 kg |
- 🗓️ Departs daily (closed Sundays + JP/TH holidays)
- ⏱️ 5-7 days
🚫 Not allowed: High-value brands (bags/watches/jewellery), gas/spray/pressurised goods, alcohol/tobacco/adult, matcha/all teas, illegal goods
🚢 Sea Cargo
| Option | Condition | Price |
|---|---|---|
| Large crate | ≤50kg · W+L+H ≤190cm | 4,000 ฿ |
| Small crate | ≤30kg · W+L+H ≤140cm | 2,500 ฿ |
| By the kilo | by weight | 150 ฿/kg |
Special items (Sea)
| Gas stove | by weight |
| Lawn mower | 1,500 ฿ |
| Bicycle | 1,800 ฿ |
| Car tyres (4) | 4,500 ฿ |
| Tyres + rims (4) | 5,000 ฿ |
| Motorcycle (as parts) | 200 ฿/kg |
| Bumper / hood (front-rear) | 200 ฿/kg |
| Front car seats (pair) | 4,500 ฿ |
| Rear seat | 3,500 ฿ |
| Fishing rod | 200 ฿/kg |
- 🗓️ Cutoff every Friday → ship departs Saturday
- ⏱️ 18-25 days
- 📦 Bulk / large volume → ask us first
🚫 Not allowed: Matcha, green tea, coffee, alcohol, tobacco, illegal goods
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