freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-178-step-numbers.md

---
id: 5900f41e1000cf542c50ff31
title: 'Problem 178: Step Numbers'
challengeType: 5
forumTopicId: 301813
dashedName: problem-178-step-numbers
---

# --description--

Consider the number 45656.

It can be seen that each pair of consecutive digits of 45656 has a difference of one.

A number for which every pair of consecutive digits has a difference of one is called a step number.

A pandigital number contains every decimal digit from 0 to 9 at least once.

How many pandigital step numbers less than ${10}^{40}$ are there?

# --hints--

`stepNumbers()` should return `126461847755`.

```js
assert.strictEqual(stepNumbers(), 126461847755);
```

# --seed--

## --seed-contents--

```js
function stepNumbers() {

  return true;
}

stepNumbers();
```

# --solutions--

```js
// solution required
```