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]])