Definition: In this task you will be given a list of lists, of numbers. For every inner list, you should multiply every number in that list and put the results in your answer. The output should be a list of numbers with the same length as the number of the lists in the input list.
Input: [[31, 26, 50, 33], [50, -46, 35, -20], [31, 18], [-4, 12, 21]]

[1329900, 1610000, 558, -1008]