# 按各国写法排的竖式计算练习单

> 一张计算练习单：每道算式是 Markdown 里 - 864 ÷ 4 这样的一行，数字一位一格排进方格，除法竖式照各国学校的写法排。

- HTML版本: https://postext.dev/zh/cookbook/column-arithmetic-by-country
- 食谱 No. 170 · 教科书 · 难度 3 (高级) · 输出: Canvas, PDF, 实时控件
- 体裁: 练习册与习题, 教科书
- 需要 postext ≥ 1.59.0, postext-pdf ≥ 1.59.0 · 已用 1.59.0, postext-pdf 1.59.0 测试，日期 2026-10-24
- 页面: [1](https://postext.dev/cookbook/column-arithmetic-by-country/es/p01.webp?v=745a9023), [2](https://postext.dev/cookbook/column-arithmetic-by-country/es/p02.webp?v=745a9023), [1](https://postext.dev/cookbook/column-arithmetic-by-country/es/p03.webp?v=745a9023), [2](https://postext.dev/cookbook/column-arithmetic-by-country/es/p04.webp?v=745a9023)
- PDF: https://postext.dev/cookbook/column-arithmetic-by-country/es/column-arithmetic-by-country.pdf?v=745a9023
- 在沙盒中打开: https://postext.dev/zh/sandbox#recipe=column-arithmetic-by-country&lang=es (.postext: https://postext.dev/cookbook/column-arithmetic-by-country/es/column-arithmetic-by-country.postext)
- 最后更新: 2026-10-24
- 其他语言: [en](https://postext.dev/en/cookbook/column-arithmetic-by-country.md), [es](https://postext.dev/es/cookbook/column-arithmetic-by-country.md), [ca](https://postext.dev/ca/cookbook/column-arithmetic-by-country.md), [de](https://postext.dev/de/cookbook/column-arithmetic-by-country.md), [fr](https://postext.dev/fr/cookbook/column-arithmetic-by-country.md), [it](https://postext.dev/it/cookbook/column-arithmetic-by-country.md), [pt](https://postext.dev/pt/cookbook/column-arithmetic-by-country.md), [ja](https://postext.dev/ja/cookbook/column-arithmetic-by-country.md), [ar](https://postext.dev/ar/cookbook/column-arithmetic-by-country.md)

## 简单来说

一页给九岁孩子做的计算题，有西班牙文、英文、法文和德文四个版本。各国写除法的方式不同，练习单照各自的写法排；一个开关能换成印好全部答案的教师版。

## 成品一览

一本四年级计算练习册的第 3 单元《四则运算》，共四个版本。先是一排分成三栏的口算，接着是加法、减法和乘法竖式，一位数字占一格，下面留一行方格写得数，最后是除法和一道印在方格纸上的应用题。各版本的差别在除法上：英文版把除数写在 ⟌ 的外面，商写在上方；西班牙文版和法文版把除数放在被除数右边的直角框里，商写在框下；德文版把 `864 : 4 =` 写成一行，下面留出写计算步骤的地方，乘号也写成圆点。口算里的小数用逗号还是小数点，同样跟着语言走。页面上方有一个开关，能把学生版换成教师版，每个答案都用橙色印在自己的格子里。

**这份食谱回答的问题:**

- 除法竖式怎样按各国学校的写法来排？
- 怎样由学生用书生成答案印在原位的教师用书？

## 简短回答

```js
// script.js, 行 26–42
// `- 864 : 4` in the Markdown is one operation; the style sets it digit by digit in squares
// of 7.2 mm, a cell for each figure of the answer. Long division follows the country: the
// divisor in an L right of the dividend in Spain and France (potence), `864 : 4 =` on one
// line in Germany, the bracket ⟌ in English-speaking schools.
const calculo = {
  id: 'calculo',
  number: { shape: 'disc', background: col('accent'), fontFamily: LABEL, fontWeight: 700 },
  instruction: { bold: true, color: col('ink') },
  grid: { cell: mm(9), fontFamily: TEXT, fontSize: pt(15), rule: col('rule'),
    color: col('ink') },
  arithmetic: { columns: 4,
    division: t({ es: 'potence', fr: 'potence', de: 'inline', en: 'bracket' }) },
  blank: { look: 'box', width: em(3.2), color: col('rule'), weight: pt(0.8) },
  area: { kind: 'grid', spacing: mm(5), color: col('rule'), weight: pt(0.4) },
  answers: { color: col('accent'), fontFamily: LABEL }, // the teacher's copy, in the accent
  marginTop: mm(7), marginBottom: mm(2), itemSpacing: em(0.5),
};
```

## 用料

**讲解**

- [竖式计算](https://postext.dev/zh/docs/exercises.md#竖式计算): 竖式计算（+ − ×），每位数字一个格；长除法按各语言学校的写法：英式 ⟌、西欧的直角式，或德式 864 : 4 = 横写。
- [教师用书](https://postext.dev/zh/docs/exercises.md#教师用书): exercises.edition: 'teacher' 把每个答案以第二种颜色印在原位，圈出正确选项：由学生用书生成教师用书。
- [练习样式](https://postext.dev/zh/docs/exercises.md#练习样式): exerciseStyles：一类练习的印刷形式，包括题号（圆、方框、标签）、题干、选项字母、空格、判断框、连线圆点、词库、书写区、格子、活动图标与难度标记。

**还用到**

- [练习](https://postext.dev/zh/docs/exercises.md#练习)
- [填空与词库](https://postext.dev/zh/docs/exercises.md#填空题与词库)
- [开放题与书写区](https://postext.dev/zh/docs/exercises.md#问答题与书写区)
- [设计过的章首页](https://postext.dev/zh/docs/configuration-headings.md#通栏与高级设计)
- [标题属性](https://postext.dev/zh/docs/document-format.md#标题属性)
- [语义调色板](https://postext.dev/zh/docs/configuration-fonts-colors-viewers.md#调色板)
- [断词与文档语言](https://postext.dev/zh/docs/justification.md#支持的语言)
- [在Canvas上绘制页面](https://postext.dev/zh/docs/configuration-programmatic-usage.md#把页面渲染为位图)
- [导出PDF](https://postext.dev/zh/docs/configuration-pdf-output.md#生成pdf)
- [段落样式](https://postext.dev/zh/docs/configuration-styles.md#段落样式)
- [框内或正文中的分栏](https://postext.dev/zh/docs/document-format-directives.md#columns)
- [答案](https://postext.dev/zh/docs/exercises.md#答案与解答)
- [嵌入PDF的字体](https://postext.dev/zh/docs/configuration-pdf-output.md#为什么需要字体提供函数)

**配置一览**

- [`bodyText`](https://postext.dev/zh/docs/configuration-text.md#正文), [`colorPalette`](https://postext.dev/zh/docs/configuration-fonts-colors-viewers.md#调色板), `exerciseStyles`, `exercises`, [`footer`](https://postext.dev/zh/docs/configuration-headers-footers.md#页眉与页脚), [`header`](https://postext.dev/zh/docs/configuration-headers-footers.md#页眉与页脚), [`headings`](https://postext.dev/zh/docs/configuration-headings.md#标题), [`layout`](https://postext.dev/zh/docs/configuration-page-layout.md#版式), [`locale`](https://postext.dev/zh/docs/configuration-language.md#断词), [`orderedLists`](https://postext.dev/zh/docs/configuration-lists-math.md#有序列表), [`page`](https://postext.dev/zh/docs/configuration-page-layout.md#页面), [`paragraphStyles`](https://postext.dev/zh/docs/configuration-styles.md#段落样式)

**API**

- [`buildDocument`](https://postext.dev/zh/docs/configuration-programmatic-usage.md#构建文档), [`buildDocumentWithFonts`](https://postext.dev/zh/docs/configuration-programmatic-usage.md#排版前加载字体), [`decompressWoff2`](https://postext.dev/zh/docs/configuration-pdf-output.md#浏览器字体提供函数fontsource--woff2), [`renderPageToCanvas`](https://postext.dev/zh/docs/configuration-programmatic-usage.md#把页面渲染为位图), [`renderToPdf`](https://postext.dev/zh/docs/configuration-pdf-output.md#生成pdf)

**字体**

- Fira Sans (OFL-1.1), Lexend (OFL-1.1)

## 做法

### 1 · 把算式写成 Markdown 里的一行

```js
// script.js, 行 26–42
// `- 864 : 4` in the Markdown is one operation; the style sets it digit by digit in squares
// of 7.2 mm, a cell for each figure of the answer. Long division follows the country: the
// divisor in an L right of the dividend in Spain and France (potence), `864 : 4 =` on one
// line in Germany, the bracket ⟌ in English-speaking schools.
const calculo = {
  id: 'calculo',
  number: { shape: 'disc', background: col('accent'), fontFamily: LABEL, fontWeight: 700 },
  instruction: { bold: true, color: col('ink') },
  grid: { cell: mm(9), fontFamily: TEXT, fontSize: pt(15), rule: col('rule'),
    color: col('ink') },
  arithmetic: { columns: 4,
    division: t({ es: 'potence', fr: 'potence', de: 'inline', en: 'bracket' }) },
  blank: { look: 'box', width: em(3.2), color: col('rule'), weight: pt(0.8) },
  area: { kind: 'grid', spacing: mm(5), color: col('rule'), weight: pt(0.4) },
  answers: { color: col('accent'), fontFamily: LABEL }, // the teacher's copy, in the accent
  marginTop: mm(7), marginBottom: mm(2), itemSpacing: em(0.5),
};
```

`:::exercise{type="arithmetic"}` 里每个列表项是一道算式，比如 `- 864 ÷ 4`，运算符号用该国学校的写法（`÷`、`:`、`×`、`·`）。得数、商和余数由引擎算出，算式怎么画由样式决定：方格边长 7.2 mm，`arithmetic.division` 用 `t()` 按版本选择。口算那一排是普通的填空题，它的列表放在 `:::columns{count=3}` 组里，每个 `[[70]]` 都是一个和其他空格一样宽的方框。

### 2 · 排练习单的页头

```js
// script.js, 行 46–67
const at = (to, edge, x = 0, y = 0, size) => ({ anchor: { to, edge },
  offset: { x: mm(x), y: mm(y) }, ...(size && { size }) });
const field = (id, attr, x, width) => [
  { kind: 'text', id, content: `{attr.${attr}}`, fontFamily: LABEL, fontSize: pt(9.5),
    fontWeight: 600, color: col('muted'), align: 'left',
    placement: at('container', 'top-left', x, 26) },
  { kind: 'rule', id: `${id}-line`, direction: 'horizontal', thickness: pt(0.75),
    color: col('rule'), placement: at('container', 'top-left', x + 17, 31, { width: mm(width) }) },
];
const head = { enabled: true, minHeight: mm(36), slot: { elements: [
  { kind: 'box', id: 'band', style: { backgroundColor: col('accent'), borderRadius: mm(3) },
    placement: at('container', 'top-left', 0, 0, { width: 'fill', height: mm(19) }) },
  { kind: 'text', id: 'unit', content: '{attr.unidad}', fontFamily: LABEL, fontSize: pt(9),
    fontWeight: 700, color: col('accent'), align: 'center', verticalAlign: 'middle',
    textTransform: 'uppercase', letterSpacing: pt(1.2), lineHeight: 1.1,
    box: { backgroundColor: col('paper'), borderRadius: mm(3.5) },
    placement: at('container', 'top-left', 5, 5, { width: mm(26), height: mm(9) }) },
  { kind: 'text', id: 'title', content: '{titleText}', fontFamily: LABEL, fontSize: pt(21),
    fontWeight: 700, color: col('paper'), align: 'left', lineHeight: 1.1,
    placement: at('container', 'top-left', 37, 5.2) },
  ...field('name', 'nombre', 0, 100), ...field('date', 'fecha', 124, 38),
] } };
```

单元的一级标题画出橙色色带、圆角块和标题，姓名和日期两栏取自标题的属性（`nombre="Name" fecha="Date"`），所以每个版本都用自己的语言来标注。

### 3 · 在学生版和教师版之间切换

```js
// script.js, 行 180–194
const form = document.getElementById('controls');
const labels = t({ es: ['Alumno', 'Profesor'], en: ['Pupil', 'Teacher'],
  fr: ['Élève', 'Enseignant'], de: ['Schüler', 'Lehrkraft'] });
form.querySelectorAll('label span').forEach((span, k) => { span.textContent = labels[k]; });
function render() {
  // The same config, edited in place: the next build sees the edition the form asks for.
  config.exercises.edition = form.elements.edition.value;
  const doc = buildDocument({ markdown }, config); // the faces are loaded by now
  showPages(doc, { title });
  document.querySelectorAll('#pt-actions a, [data-postext-pdf]').forEach((old) => old.remove());
  offerPdf(() => renderToPdf(doc, { fontProvider: fontsourceProvider }),
    `${RECIPE}-${LANG}-${config.exercises.edition}.pdf`);
}
form.addEventListener('change', render);
render();
```

`exercises.edition: 'teacher'` 把每个答案印在它的位置上，颜色取自 `answers.color`，这里用的是强调色：口算的方框、每道题得数的各位数字、商和余数，以及应用题的参考答案。页面上方的表单直接修改配置并重新排版；字体已经加载，所以用普通的 `buildDocument` 就够了。截图时会先把两份练习单都排好，所以发布的页面先是学生版，后是教师版。

## 完整食谱

下面的文件由食谱文件夹合成，示例文本和排版食谱的公共工具包都已内联。要把它们作为一个页面运行，把HTML放进`<body>`，CSS放进`<style>`元素，脚本放进`<script type="module">`；也可以把它们分别粘贴到新建CodePen的对应面板里（JS设为模块）。脚本从esm.sh导入postext，不需要安装或构建。

- 食谱文件夹: https://github.com/drnachio/postext/tree/main/cookbook/column-arithmetic-by-country

### index.html

```html
<form id="controls" aria-label="Edition">
  <label><input type="radio" name="edition" value="student" checked> <span></span></label>
  <label><input type="radio" name="edition" value="teacher"> <span></span></label>
</form>
<main id="pages"></main>
```

### style.css

```css
/* The edition switch above the desk: two pills in the sheet's orange. */
#controls {
  display: flex; justify-content: center; gap: 8px; padding: 14px 16px; background: #16181d;
  font: 600 14px/1.2 Lexend, system-ui, sans-serif;
}
#controls label {
  display: inline-flex; align-items: center; gap: 6px; min-height: 44px; padding: 0 18px;
  border-radius: 22px; color: #f4f1ea; border: 1px solid #5f6670; cursor: pointer;
}
#controls label:has(input:checked) { background: #c4511c; border-color: #c4511c; }
#controls input { accent-color: #fff; }
```

### script.js

```js
// ═══ Postext Cookbook · Nº 170 · Column arithmetic as each country writes it ═══════
// https://postext.dev/en/cookbook/column-arithmetic-by-country
// Code: MIT · Text: original (CC BY 4.0) · Pictures: none
// Fonts: Fira Sans, Lexend (SIL OFL 1.1) · Needs postext ≥ 1.59.0
import { buildDocumentWithFonts, buildDocument, renderPageToCanvas } from 'https://esm.sh/postext';
import { renderToPdf, decompressWoff2 } from 'https://esm.sh/postext-pdf';

const LANG = 'es'; // @lang: the language of the worksheet ('es' | 'en' | 'fr' | 'de')
const RECIPE = 'column-arithmetic-by-country';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
// #region palette: ink, one orange accent, a pale tint, the grey of squared paper
const palette = {
  ink: '#1f2328', accent: '#c4511c', tint: '#fbeee6', rule: '#b9c0c8', muted: '#5f6670',
  paper: '#ffffff',
};
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
const colorPalette = [
  ...Object.entries(palette).map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } })),
  { id: 'main-color', name: 'accent (defaults)', value: { hex: palette.accent, model: 'hex' } },
];
// #endregion
const [TEXT, LABEL] = ['Fira Sans', 'Lexend'];

// #region answer: operations in squares, long division as the edition's schools set it
// `- 864 : 4` in the Markdown is one operation; the style sets it digit by digit in squares
// of 7.2 mm, a cell for each figure of the answer. Long division follows the country: the
// divisor in an L right of the dividend in Spain and France (potence), `864 : 4 =` on one
// line in Germany, the bracket ⟌ in English-speaking schools.
const calculo = {
  id: 'calculo',
  number: { shape: 'disc', background: col('accent'), fontFamily: LABEL, fontWeight: 700 },
  instruction: { bold: true, color: col('ink') },
  grid: { cell: mm(9), fontFamily: TEXT, fontSize: pt(15), rule: col('rule'),
    color: col('ink') },
  arithmetic: { columns: 4,
    division: t({ es: 'potence', fr: 'potence', de: 'inline', en: 'bracket' }) },
  blank: { look: 'box', width: em(3.2), color: col('rule'), weight: pt(0.8) },
  area: { kind: 'grid', spacing: mm(5), color: col('rule'), weight: pt(0.4) },
  answers: { color: col('accent'), fontFamily: LABEL }, // the teacher's copy, in the accent
  marginTop: mm(7), marginBottom: mm(2), itemSpacing: em(0.5),
};
// #endregion

// #region head: the unit pill, the title and the lines for a name and a date
const at = (to, edge, x = 0, y = 0, size) => ({ anchor: { to, edge },
  offset: { x: mm(x), y: mm(y) }, ...(size && { size }) });
const field = (id, attr, x, width) => [
  { kind: 'text', id, content: `{attr.${attr}}`, fontFamily: LABEL, fontSize: pt(9.5),
    fontWeight: 600, color: col('muted'), align: 'left',
    placement: at('container', 'top-left', x, 26) },
  { kind: 'rule', id: `${id}-line`, direction: 'horizontal', thickness: pt(0.75),
    color: col('rule'), placement: at('container', 'top-left', x + 17, 31, { width: mm(width) }) },
];
const head = { enabled: true, minHeight: mm(36), slot: { elements: [
  { kind: 'box', id: 'band', style: { backgroundColor: col('accent'), borderRadius: mm(3) },
    placement: at('container', 'top-left', 0, 0, { width: 'fill', height: mm(19) }) },
  { kind: 'text', id: 'unit', content: '{attr.unidad}', fontFamily: LABEL, fontSize: pt(9),
    fontWeight: 700, color: col('accent'), align: 'center', verticalAlign: 'middle',
    textTransform: 'uppercase', letterSpacing: pt(1.2), lineHeight: 1.1,
    box: { backgroundColor: col('paper'), borderRadius: mm(3.5) },
    placement: at('container', 'top-left', 5, 5, { width: mm(26), height: mm(9) }) },
  { kind: 'text', id: 'title', content: '{titleText}', fontFamily: LABEL, fontSize: pt(21),
    fontWeight: 700, color: col('paper'), align: 'left', lineHeight: 1.1,
    placement: at('container', 'top-left', 37, 5.2) },
  ...field('name', 'nombre', 0, 100), ...field('date', 'fecha', 124, 38),
] } };
// #endregion

const config = {
  locale: t({ es: 'es', en: 'en-gb', fr: 'fr', de: 'de' }),
  colorPalette,
  page: { sizePreset: 'custom', width: mm(210), height: mm(297), dpi: 150,
    margins: { top: mm(18), bottom: mm(20), left: mm(18), right: mm(18), mirror: true } },
  layout: { layoutType: 'single' },
  bodyText: {
    fontFamily: TEXT, fontSize: pt(12), lineHeight: pt(18), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
    textAlign: 'left', firstLineIndent: pt(0), hyphenation: { enabled: false },
    optimalLineBreaking: true, avoidWidows: true, avoidOrphans: true, avoidRunts: true,
  },
  headings: { fontFamily: LABEL, color: col('ink'), fontWeight: 700, levels: [
    { level: 1, fontSize: pt(21), breakBefore: { parity: 'any' }, marginTop: pt(0),
      marginBottom: mm(1), advancedDesign: head },
  ] },
  exerciseStyles: [calculo],
  exercises: { edition: 'student' }, // the switch above the pages sets 'teacher'
  orderedLists: { fontFamily: LABEL, numberFormat: 'arabic', color: col('accent'),
    fontWeight: 600, marginTop: pt(0), marginBottom: pt(0) },
  paragraphStyles: [{ id: 'colofon', fontFamily: TEXT, fontSize: pt(7.5), lineHeight: pt(10),
    color: col('muted'), firstLineIndent: pt(0), marginTop: mm(6) }],
  header: { elements: [] },
  footer: { elements: [{ kind: 'text', id: 'folio', content: '{pageNumber}', fontFamily: LABEL,
    fontSize: pt(9), fontWeight: 700, color: col('accent'), align: 'center',
    placement: at('page', 'bottom', 0, -11) }] },
};

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
title: "Matemáticas 4"
subtitle: "Cuaderno de cálculo"
---

# Las cuatro operaciones {unidad="Unidad 3" nombre="Nombre" fecha="Fecha"}

:::exercise{type="gaps"}
Calcula mentalmente y escribe el resultado.

:::columns{count=3}
1. 40 + 30 = [[70]]
2. 90 − 25 = [[65]]
3. 7 × 8 = [[56]]
4. 63 : 9 = [[7]]
5. 250 + 750 = [[1000]]
6. 1000 − 400 = [[600]]
7. 0,5 + 0,25 = [[0,75]]
8. 1,5 × 2 = [[3]]
9. 4,8 : 2 = [[2,4]]
:::
:::

:::exercise{type="arithmetic"}
Coloca las cifras en columna y suma.

- 4567 + 2385
- 3528 + 1764
- 806 + 1497
:::

:::exercise{type="arithmetic"}
Resta y comprueba con una suma.

- 7302 − 2865
- 5040 − 1376
- 913 − 458
:::

:::exercise{type="arithmetic"}
Multiplica.

- 437 × 6
- 1209 × 8
- 365 × 7
:::

:::exercise{type="arithmetic"}
Divide. Cuando la división no sea exacta, escribe también el resto.

- 864 : 4
- 1575 : 5
- 917 : 7
- 638 : 3
:::

:::exercise{type="open" lines="6"}
Una caja de lápices de colores cuesta 3,75 €. ¿Cuánto cuestan cuatro cajas? Si pagas con un billete de 20 €, ¿cuánto te devuelven?

:::solution
Cuatro cajas cuestan 3,75 € × 4 = 15 €. Te devuelven 20 € − 15 € = 5 €.
:::
:::

:::paragraphs{style="colofon"}
Compuesto en Lexend y Fira Sans (SIL OFL) · Texto original (CC BY 4.0)
:::
`; // content.<lang>.md, inlined by the Cookbook

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = { 'Fira Sans': ['400', '700'], Lexend: ['600', '700'] };

// ─── 4 · Build & show ───────────────────────────────────────────────────────
const title = t({ es: 'Cuaderno de cálculo', en: 'Calculation book', fr: 'Cahier de calcul',
  de: 'Rechenheft' });
// The pupil's sheet first, then the teacher's copy: the capture shows both.
await buildDocumentWithFonts({ markdown }, config, kitFonts(FONTS));
config.exercises.edition = 'teacher';
buildDocument({ markdown }, config);

// #region live: a switch between the pupil's sheet and the teacher's copy
const form = document.getElementById('controls');
const labels = t({ es: ['Alumno', 'Profesor'], en: ['Pupil', 'Teacher'],
  fr: ['Élève', 'Enseignant'], de: ['Schüler', 'Lehrkraft'] });
form.querySelectorAll('label span').forEach((span, k) => { span.textContent = labels[k]; });
function render() {
  // The same config, edited in place: the next build sees the edition the form asks for.
  config.exercises.edition = form.elements.edition.value;
  const doc = buildDocument({ markdown }, config); // the faces are loaded by now
  showPages(doc, { title });
  document.querySelectorAll('#pt-actions a, [data-postext-pdf]').forEach((old) => old.remove());
  offerPdf(() => renderToPdf(doc, { fontProvider: fontsourceProvider }),
    `${RECIPE}-${LANG}-${config.exercises.edition}.pdf`);
}
form.addEventListener('change', render);
render();
// #endregion

// ─── Kit ── helpers shared by every Cookbook recipe · postext.dev/cookbook ─────

// ─── Kit · core v1 ── the same in every recipe · postext.dev/cookbook
function mm(value) { return { value, unit: 'mm' }; }
function pt(value) { return { value, unit: 'pt' }; }
function em(value) { return { value, unit: 'em' }; }
/** The sample language's string: t({ en: 'Figure', es: 'Figura' }). */
function t(strings) { return strings[LANG] ?? Object.values(strings)[0]; }
/** A file in this recipe's assets folder, served from the Postext repo by jsDelivr. */
function asset(file) { return `https://cdn.jsdelivr.net/gh/drnachio/postext@main/cookbook/${RECIPE}/assets/${file}`; }

// ─── Kit · fonts v3 ── the same in every recipe · postext.dev/cookbook
// Postext loads the faces a config asks for before layout and asks the kit
// for Fontsource's files, the ones the PDF embeds too.

/** buildDocumentWithFonts' options: the resolver, and FONTS' faces loaded
 *  with the config's. FONTS = { 'Family Name': ['400', '400i', '700'] }. */
function kitFonts(FONTS = {}) {
  const faces = Object.entries(FONTS).flatMap(([family, specs]) => specs.map((spec) =>
    ({ family, weight: parseInt(spec, 10), style: spec.endsWith('i') ? 'italic' : 'normal' })));
  return { resolve: fontsourceResolver, faces };
}

/** A face's files with their ranges: latin, then latin-ext and greek when
 *  `text` needs them (kitSubsetsFor). Null for a face Fontsource lacks. */
async function fontsourceResolver(family, weight, style, { text = '' } = {}) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  if (meta && !(await fontsourceWeights(family, style)).includes(weight)) return null;
  kitStatus('Loading fonts…');
  const at = await fontsourceAt(id);
  return ['latin', ...kitSubsetsFor(text, meta)].map((subset) => ({
    source: `${at}files/${id}-${subset}-${weight}-${style}.woff2`,
    unicodeRange: kitRanges()[subset],
  }));
}

/** Each file's unicode-range (a function: the kit runs after the pen's code). */
function kitRanges() {
  return {
    latin: 'U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,'
      + 'U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD',
    'latin-ext': 'U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,'
      + 'U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF',
    greek: 'U+0370-03FF',
  };
}

/** For the cjk, arabic and comics blocks: loads `faces` (as FONTS) for the
 *  sample `text`; `optional` skips a face Fontsource lacks. Files are added in
 *  the order asked, the last winning a shared character. Resolves to the count. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = kitRanges();
  const jobs = [];
  for (const [family, specs] of Object.entries(faces)) {
    const id = fontsourceId(family);
    const todo = [...new Set(specs)].map((spec) => [parseInt(spec, 10), spec.endsWith('i') ? 'italic' : 'normal'])
      .filter(([weight, style]) => !hasFace(family, weight, style)); // before any await
    const at = fontsourceAt(id);
    const meta = optional || /[^\0-ÿ]/u.test(text) ? await fontsourceMeta(family) : null;
    const subsets = ['latin', ...kitSubsetsFor(text, meta)];
    for (const [weight, style] of todo) {
      if (optional && !(meta && (await fontsourceWeights(family, style)).includes(weight))) continue;
      for (const subset of subsets) {
        const url = `${await at}files/${id}-${subset}-${weight}-${style}.woff2`;
        const face = new FontFace(family, `url(${url}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: ranges[subset] });
        jobs.push(face.load().catch(() => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  const ready = await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return ready.filter((face) => face && document.fonts.add(face)).length;
}

/** A loaded FontFace covers this face (fonts.check() says yes to any family). */
function hasFace(family, weight, style) {
  for (const face of document.fonts) {
    if (face.status !== 'loaded' || face.style !== style) continue;
    if (face.family.replace(/^["']|["']$/g, '') !== family) continue;
    const [low, high = low] = face.weight.split(' ').map(Number);
    if (weight >= low && weight <= high) return true;
  }
  return false;
}

/** The files beyond latin `text` needs that `meta`'s family ships. */
function kitSubsetsFor(text, meta) {
  return [[/[Ā-˿ᴀ-ᶿḀ-ỿ†ℓⱠ-Ɀ꜠-ꟿ]/u, 'latin-ext'], [/[Ͱ-Ͽ]/u, 'greek']]
    .filter(([re, x]) => re.test(text) && meta?.subsets?.includes(x)).map(([, x]) => x);
}

/** Fontsource's id for a family: 'Source Serif 4' → 'source-serif-4'. */
function fontsourceId(family) { return family.toLowerCase().replace(/\s+/g, '-'); }

/** A package's folder at the one version @5 names now (#766). */
function fontsourceAt(id, u = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@`) {
  return (fontsourceAt.c ??= {})[id] ??= fetch(u + '5/package.json').then((r) => r.json())
    .then((p) => p.version || 5, () => 5).then((v) => `${u}${v}/`);
}

/** The family's Fontsource metadata (weights, styles, subsets), or null. */
function fontsourceMeta(family, id = fontsourceId(family)) {
  return (fontsourceMeta.c ??= {})[id] ??= fetch(`https://api.fontsource.org/v1/fonts/${id}`)
    .then((res) => (res.ok ? res.json() : null), () => null);
}

/** The weights the package ships in `style`: the API pairs none (no Libre
 *  Caslon 700 italic file), so italics are read from latin-italic.css. */
function fontsourceWeights(family, style, id = fontsourceId(family)) {
  return (fontsourceWeights.c ??= {})[id + style] ??= fontsourceMeta(family).then(async (m) => {
    if (!m?.styles.includes(style)) return m ? [] : [400, 700];
    const css = style === 'italic' ? await fetch(`${await fontsourceAt(id)}latin-italic.css`).then((r) => (r.ok ? r.text() : ''), () => '') : '';
    const w = [...css.matchAll(/weight: (\d+)/g)].map((x) => +x[1]);
    return w.length ? w : m.weights;
  });
}

// ─── Kit · viewer v2 ── the same in every recipe · postext.dev/cookbook
/** The pages as spreads on a dark desk, page 1 alone, then verso | recto,
 *  each painted when it scrolls near. Other options go to renderPageToCanvas. */
function showPages(docs, { title, width = 460, ...render } = {}) {
  const root = viewer(title);
  const pages = [docs].flat().flatMap((doc) =>
    doc.pages.map((page) => ({ doc, page, n: (doc.pageIndexOffset ?? 0) + page.index })));
  const spreads = [];
  let verso = null;
  for (const p of pages) {
    if (p.n % 2 === 1) { if (verso) spreads.push([verso, null]); verso = p; }
    else { spreads.push([verso, p]); verso = null; }
  }
  if (verso) spreads.push([verso, null]);
  const density = Math.min(window.devicePixelRatio || 1, 2);
  showPages.painter?.disconnect();
  const painter = new IntersectionObserver((entries) => {
    for (const { isIntersecting, target } of entries) {
      if (!isIntersecting) continue;
      painter.unobserve(target);
      const { doc, page } = target.postext;
      renderPageToCanvas(page, doc, target, { ...render, scale: (width * density) / page.width });
    }
  }, { rootMargin: '800px' });
  showPages.painter = painter;
  root.replaceChildren(...spreads.map((pair) => {
    const spread = document.createElement('div');
    spread.className = 'pt-spread';
    for (const p of pair) {
      const figure = document.createElement('figure');
      if (p) {
        const label = p.page.pageLabel || String(p.n + 1);
        const canvas = document.createElement('canvas');
        canvas.postext = p;
        canvas.style.aspectRatio = `${p.page.width} / ${p.page.height}`;
        canvas.setAttribute('role', 'img');
        canvas.setAttribute('aria-label', `Page ${label}`);
        const folio = document.createElement('figcaption');
        folio.textContent = label;
        figure.append(canvas, folio);
        painter.observe(canvas);
      } else figure.className = 'pt-blank';
      spread.append(figure);
    }
    return spread;
  }));
  kitStatus(`${pages.length} ${pages.length === 1 ? 'page' : 'pages'}`);
  document.documentElement.dataset.postext = 'ready';
  return pages.length;
}

/** The desk, the bar and the error reporting, created once. */
function viewer(title) {
  if (!document.getElementById('pt-kit')) {
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit">
      :root { color-scheme: dark; }
      body { margin: 0; background: #0e1014; color: #b9bcc4; font: 13px/1.45 system-ui, sans-serif; }
      #pt-bar { position: sticky; top: 0; z-index: 1; display: flex; flex-wrap: wrap; align-items: center;
        gap: 6px 16px; padding: 10px 16px; background: rgb(14 16 20 / .92); backdrop-filter: blur(6px);
        border-bottom: 1px solid #23262d; }
      #pt-bar strong { color: #f4f1ea; font-weight: 600; }
      #pt-actions { display: flex; gap: 12px; margin-left: auto; }
      #pt-actions a, #pt-actions button { color: #d8a21a; font: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
      #pages { display: grid; justify-items: center; gap: 48px; padding: 32px 16px 72px; }
      .pt-spread { display: flex; }
      .pt-spread figure { margin: 0; width: min(460px, 44vw); }
      .pt-spread canvas { display: block; width: 100%; background: #fff;
        box-shadow: 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figure:first-child canvas { box-shadow: inset -14px 0 14px -14px rgb(0 0 0 / .18), 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figcaption { margin-top: 10px; text-align: center; font: 600 10px/1 system-ui, sans-serif;
        letter-spacing: .18em; text-transform: uppercase; color: #6c7079; }
      .pt-blank { visibility: hidden; }
      @media (max-width: 760px) {
        .pt-spread { flex-direction: column; gap: 32px; }
        .pt-spread figure { width: min(460px, 92vw); }
        .pt-blank { display: none; }
      }
    </style>`);
    document.body.insertAdjacentHTML('afterbegin',
      '<header id="pt-bar"><strong id="pt-title"></strong><span id="pt-status" role="status"></span><span id="pt-actions"></span></header>');
    document.getElementById('pt-title').textContent = document.title || 'Postext';
    addEventListener('error', (event) => kitFail(event.error ?? event.message));
    addEventListener('unhandledrejection', (event) => kitFail(event.reason));
  }
  if (title) document.getElementById('pt-title').textContent = title;
  return document.getElementById('pages')
    ?? document.body.appendChild(Object.assign(document.createElement('main'), { id: 'pages' }));
}

function kitStatus(text) {
  viewer();
  document.getElementById('pt-status').textContent = text;
}

function kitFail(error) {
  document.documentElement.dataset.postext = 'error';
  kitStatus(`Error: ${error?.message ?? error}`);
}

// ─── Kit · pdf v3 ── the same in every recipe that exports a PDF
/** The Fontsource files the screen used, as TrueType, with their range and
 *  place: the nearest weight the family ships in that style, upright with no italic;
 *  latin, then what its letters need (kitSubsetsFor). */
async function fontsourceProvider(family, weight, style, request) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  const s = style === 'italic' && meta && !meta.styles.includes('italic') ? 'normal' : style;
  const shipped = meta ? await fontsourceWeights(family, s) : [];
  const weights = shipped.length ? shipped : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const text = String.fromCodePoint(...(request?.codePoints ?? []));
  const files = await Promise.all(['latin', ...kitSubsetsFor(text, meta)].map(async (subset, order) => {
    const res = await fetch(`${await fontsourceAt(id)}files/${id}-${subset}-${w}-${s}.woff2`);
    if (!res.ok) throw new Error(`Fontsource has no ${family} ${w} ${s} ${subset}`);
    return Object.assign(await decompressWoff2(new Uint8Array(await res.arrayBuffer())),
      { unicodeRange: kitRanges()[subset], order });
  }));
  return files.length === 1 ? files[0] : files;
}

/** A "Build the PDF" button; then "Open the PDF" (a new tab: CodePen's frame
 *  shows no PDFs) and a download link. */
function offerPdf(makePdf, filename) {
  viewer();
  const button = Object.assign(document.createElement('button'), { type: 'button', textContent: 'Build the PDF' });
  button.dataset.postextPdf = filename;
  button.addEventListener('click', async () => {
    button.disabled = true;
    button.textContent = 'Building the PDF…';
    try {
      const bytes = await makePdf();
      const url = URL.createObjectURL(new Blob([bytes], { type: 'application/pdf' }));
      const size = `${Math.max(1, Math.round(bytes.length / 1024))} KB`;
      button.replaceWith(
        Object.assign(document.createElement('a'), { href: url, target: '_blank', rel: 'noopener', textContent: 'Open the PDF ↗' }),
        Object.assign(document.createElement('a'), { href: url, download: filename, textContent: `Download ${filename} · ${size}` }));
    } catch (error) {
      button.disabled = false;
      button.textContent = 'Build the PDF';
      kitFail(error);
    }
  });
  document.getElementById('pt-actions').append(button);
}

// ─── /Kit ───────────────────────────────────────────────────────────────────────
```

## 变化

### 把答案倒印在题目下方

这是谜题书的老做法：每道题的答案旋转 180°，印在题目下面。

```diff
-  exercises: { edition: 'student' }, // the switch above the pages sets 'teacher'
+  exercises: { edition: 'student', solutions: { placement: 'inverted', layout: 'key' } },
```

### 所有版本都用 ⟌ 写除法

中国和日本的学校也用这种除法竖式；没有列出的语言使用它自己的默认写法。

```diff
-    division: t({ es: 'potence', fr: 'potence', de: 'inline', en: 'bracket' }) },
+    division: 'bracket' },
```

## 常见问题

- 算式只接受整数：带小数的算式，比如 `12,5 + 3,75`，不会被识别，会按原样印出来。小数请留在口算的填空里，那里的答案是文字。

## 致谢

- 食谱: Ignacio Ferro ([@drnachio](https://github.com/drnachio))
- 字体: Fira Sans (OFL-1.1), Lexend (OFL-1.1)
- 代码: MIT · 示例内容: CC-BY-4.0

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