If you have a multi-dimensional array, you can use the same logic as the prior waypoint to loop through both the array and any sub-arrays. Here is an example:
```js
let arr = [[1,2], [3,4], [5,6]];
for (let i=0; i < arr.length; i++) {
for (let j=0; j < arr[i].length; j++) {
console.log(arr[i][j]);
}
}
```
This outputs each sub-element in `arr` one at a time. Note that for the inner loop, we are checking the `.length` of `arr[i]`, since `arr[i]` is itself an array.
```js
function multiplyAll(arr) {
let product = 1;
for (let i = 0; i < arr.length; i++) {
for (let j = 0; j < arr[i].length; j++) {
product *= arr[i][j];
}
}
return product;
}
multiplyAll([[1,2],[3,4],[5,6,7]]); // 5040
```