In this task, you are given an input list A. You need to find all the elements of the list that are numbers and calculate their sum.

Example Input: ['M', 'H', 'l', 'Y', '3811', '1953', '5869', 'U']
Example Output: 11633

Example Input: ['5573', '6221', 'C', '8649', '6603', 'q', '9403']
Example Output: 36449

Example Input: ['8673', 'U', '8927', 'W']
Example Output:
17600