---
id: 5900f3941000cf542c50fea7
challengeType: 5
videoUrl: ''
title: 问题40：Champernowne的常数
---

## Description
<section id="description">通过连接正整数创建无理小数： <span style="display: block; text-align: center;">0.12345678910 <b style="color: red;">1</b> 112131415161718192021 ...</span>可以看出小数部分的<sup>第</sup> 12位是1.如果<i>d <sub>n</sub></i>代表小数部分的<sup>第</sup> <i>n</i>位，找到值以下表达式。 <span style="display: block; text-align: center;">d <sub>1</sub> ×d <sub>10</sub> ×d <sub>100</sub> ×d <sub>1000</sub> ×d <sub>10000</sub> ×d <sub>100000</sub> ×d <sub>1000000</sub></span> </section>

## Instructions
<section id="instructions">
</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>champernownesConstant(100)</code>应该返回5。
    testString: assert.strictEqual(champernownesConstant(100), 5);
  - text: <code>champernownesConstant(1000)</code>应该返回15。
    testString: assert.strictEqual(champernownesConstant(1000), 15);
  - text: <code>champernownesConstant(1000000)</code>应该返回210。
    testString: assert.strictEqual(champernownesConstant(1000000), 210);

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='js-seed'>

```js
function champernownesConstant(n) {
  // Good luck!
  return true;
}

champernownesConstant(100);

```

</div>



</section>

## Solution
<section id='solution'>

```js
// solution required
```

/section>