---
id: 5900f3e41000cf542c50fef7
challengeType: 5
title: 'Problem 120: Square remainders'
videoUrl: ''
localeTitle: 问题120：方形剩余部分
---

## Description
<section id="description">设r是（a-1）n +（a + 1）n除以a2时的余数。例如，如果a = 7且n = 3，则r = 42：63 + 83 =728≡42mod 49.并且当n变化时，r也将变化，但是对于a = 7，结果是rmax = 42。对于3≤a≤1000，找到Σrmax。 </section>

## Instructions
<section id="instructions">
</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>euler120()</code>应返回333082500。
    testString: 'assert.strictEqual(euler120(), 333082500, "<code>euler120()</code> should return 333082500.");'

```

</section>

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

<div id='js-seed'>

```js
function euler120() {
  // Good luck!
  return true;
}

euler120();

```

</div>



</section>

## Solution
<section id='solution'>

```js
// solution required
```
</section>