freeCodeCamp/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-222-sphere-packing.english.md

---
id: 5900f44b1000cf542c50ff5d
challengeType: 5
title: 'Problem 222: Sphere Packing'
---

## Description
<section id='description'>
What is the length of the shortest pipe, of internal radius 50mm, that can fully contain 21 balls of radii 30mm, 31mm, ..., 50mm?

Give your answer in micrometres (10-6 m) rounded to the nearest integer.
</section>

## Instructions
<section id='instructions'>

</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>euler222()</code> should return 1590933.
    testString: assert.strictEqual(euler222(), 1590933, '<code>euler222()</code> should return 1590933.');

```

</section>

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

<div id='js-seed'>

```js
function euler222() {
  // Good luck!
  return true;
}

euler222();
```

</div>



</section>

## Solution
<section id='solution'>

```js
// solution required
```
</section>