freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-43-sub-string-divisibility.english.md

---
id: 5900f3971000cf542c50feaa
challengeType: 5
isHidden: false
title: 'Problem 43: Sub-string divisibility'
forumTopicId: 302100
---

## Description
<section id='description'>

The number, 1406357289, is a 0 to 9 pandigital number because it is made up of each of the digits 0 to 9 in some order, but it also has a rather interesting sub-string divisibility property.

Let d<sub>1</sub> be the 1<sup>st</sup> digit, d<sub>2</sub> be the 2<sup>nd</sup> digit, and so on. In this way, we note the following:

<ul>
  <li>d<sub>2</sub>d<sub>3</sub>d<sub>4</sub> = 406 is divisible by 2</li>
  <li>d<sub>3</sub>d<sub>4</sub>d<sub>5</sub> = 063 is divisible by 3</li>
  <li>d<sub>4</sub>d<sub>5</sub>d<sub>6</sub> = 635 is divisible by 5</li>
  <li>d<sub>5</sub>d<sub>6</sub>d<sub>7</sub> = 357 is divisible by 7</li>
  <li>d<sub>6</sub>d<sub>7</sub>d<sub>8</sub> = 572 is divisible by 11</li>
  <li>d<sub>7</sub>d<sub>8</sub>d<sub>9</sub> = 728 is divisible by 13</li>
  <li>d<sub>8</sub>d<sub>9</sub>d<sub>10</sub> = 289 is divisible by 17</li>
</ul>

Find the numbers of all 0 to 9 pandigital numbers with this property.

</section>

## Instructions
<section id='instructions'>

</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>substringDivisibility()</code> should return an array.
    testString: assert(Array.isArray(substringDivisibility()));
  - text: <code>substringDivisibility()</code> should return [ 1430952867, 1460357289, 1406357289, 4130952867, 4160357289, 4106357289 ].
    testString: assert.sameMembers(substringDivisibility(), [ 1430952867, 1460357289, 1406357289, 4130952867, 4160357289, 4106357289 ]);
  - text: You should not copy and return the array.
    testString: assert(!removeJSComments(code).match(/(1430952867)|(1460357289)|(1406357289)|(4130952867)|(4160357289)|(4106357289)/))

```

</section>

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

<div id='js-seed'>

```js
function substringDivisibility() {
  // Good luck!
  return [];
}

substringDivisibility();
```

</div>

### After Test
<div id='js-teardown'>

```js
const removeJSComments = str => str.replace(/\/\*[\s\S]*?\*\/|\/\/.*$/gm, '');
```

</div>

</section>

## Solution
<section id='solution'>

```js
// solution required
```

</section>