i and j are index values. You need to use them to get to the elements inside the arrays. Them multiply the elements (not the indexes). Look at the example code on how to access the elements. for (let i = 0; i < arr.length; i++) { for (let j = 0; j < arr[i].length; j++) { console.log(arr[i][j…

This is what nesting does, for each iteration of the outer loop, the inner one loops until the breaking condition is met. for (let i = 0; i < arr.length; i++) { for (let j = 0; j < arr[i].length; j++) { console.log(i, j); } } i.e. Outer loop - i == 0, inner loop will run from j == 0 to j < …

Let’s add some printouts: for (let i = 0; i < arr.length; i++) { console.log('i', i); console.log(`arr[${i}]`, arr[i]); for (let j = 0; j < arr[i].length; j++) { console.log(' j', j) console.log(` arr[${i}][${j}]`, arr[i][j]) } } Does this helps?

length instead of lenght :slight_smile:

There are sub arrays in the default parameter passed to multiplyAll, it's passed multiplyAll([[1,2],[3,4],[5,6,7]]); in the code. That's an array that contains 3 sub arrays.

You need to modify the function so it does what is asked and returns the result, the exercise is setup technically that when you press the run tests buttons it will take care of sending your function proper test data (2D arrays). They come to you in the shape of the arr variable in multiplyAll. arrwill be an array with sub arrays.

Does that make sense?