---
id: 5900f43a1000cf542c50ff4d
challengeType: 5
title: 'Problem 206: Concealed Square'
---
## Description
Find the unique positive integer whose square has the form 1_2_3_4_5_6_7_8_9_0, where each “_” is a single digit.
## Instructions
## Tests
```yml
tests:
- text: euler206() should return 1389019170.
testString: assert.strictEqual(euler206(), 1389019170);
```
## Challenge Seed
```js
function euler206() {
// Good luck!
return true;
}
euler206();
```