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.
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Question: ['Q', '9787', '7533', '9489', 'C', '1753', '5121', '1405', '9267', '4815', 's', '5887']

Answer: 55057


Question: ['3557', '3345', '307', '9791', '1897', 'O']

Answer: 18897


Question: ['5993', '5767']

Answer:
11760