**Tell us what’s happening:**

I’m confused in the return line

(a,b)=> a + b, 0)

what is the use of adding 0 to this line??

**Your code so far**

```
const sum = (...args) => {
return args.reduce((a, b) => a + b, 0);
}
```

**Your browser information:**

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36`

**Challenge:** ES6 - Use the Rest Parameter with Function Parameters

**Link to the challenge:**

The 0 is the initial value for the `reduce`

method.

I’m unable to understand reduce method

can you please explain with an example??

The reduce method isn’t part of this Challenge.

It will be covered in this Challenge: