---
id: 5900f4ed1000cf542c50ffff
title: 'Problem 383: Divisibility comparison between factorials'
challengeType: 5
forumTopicId: 302047
dashedName: problem-383-divisibility-comparison-between-factorials
---

# --description--

Let f5(n) be the largest integer x for which 5x divides n.

For example, f5(625000) = 7.

Let T5(n) be the number of integers i which satisfy f5((2·i-1)!) < 2·f5(i!) and 1 ≤ i ≤ n. It can be verified that T5(103) = 68 and T5(109) = 2408210.

Find T5(1018).

# --hints--

`euler383()` should return 22173624649806.

```js
assert.strictEqual(euler383(), 22173624649806);
```

# --seed--

## --seed-contents--

```js
function euler383() {

  return true;
}

euler383();
```

# --solutions--

```js
// solution required
```