freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-222-sphere-packing.md

---
id: 5900f44b1000cf542c50ff5d
title: 'Problem 222: Sphere Packing'
challengeType: 5
forumTopicId: 301865
dashedName: problem-222-sphere-packing
---

# --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.

# --hints--

`euler222()` should return 1590933.

```js
assert.strictEqual(euler222(), 1590933);
```

# --seed--

## --seed-contents--

```js
function euler222() {

  return true;
}

euler222();
```

# --solutions--

```js
// solution required
```