**Tell us what’s happening:**

@KBPsystem777

I figured the solution out and saw your posts on this topic, but can someone please explain to me why product *= arr[i][j]; work? specifically the arr[i][j] with [i][j] stacked next to each other… was there a lesson I forgot/missed? I understand *= is to multiply all of it… just the [i][j] next together is confusing to me… thanks

**Your code so far**

```
function multiplyAll(arr) {
var product = 1;
// Only change code below this line
for (var i = 0; i < arr.length; i++) {
for (var j = 0; j < arr[i].length; j++) {
product *= arr[i][j];
}
}
// Only change code above this line
return product;
}
// Modify values below to test your code
multiplyAll([[1,2],[3,4],[5,6,7]]);
```

**Your browser information:**

Your Browser User Agent is: `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36`

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**Link to the challenge:**