freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-432-totient-sum.md

---
id: 5900f51e1000cf542c510030
title: 'Problem 432: Totient sum'
challengeType: 5
forumTopicId: 302103
dashedName: problem-432-totient-sum
---

# --description--

Let $S(n, m) = \sum φ(n × i)$ for $1 ≤ i ≤ m$. ($φ$ is Euler's totient function)

You are given that $S(510\\,510, {10}^6) = 45\\,480\\,596\\,821\\,125\\,120$.

Find $S(510\\,510, {10}^{11})$. Give the last 9 digits of your answer.

# --hints--

`totientSum()` should return `754862080`.

```js
assert.strictEqual(totientSum(), 754862080);
```

# --seed--

## --seed-contents--

```js
function totientSum() {

  return true;
}

totientSum();
```

# --solutions--

```js
// solution required
```