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: ['R', 'J', 'z', 'o', '1121', '7247', '8987', 'u']
Example Output: 17355

Example Input: ['4425', 'x', '1959', 'C', 'c', 'D', 'M', '8317', 'q', 'x', '4277', 'N', 'z', 'I', '1921', 'o', 't']
Example Output: 20899

Example Input: ['c', '2361', '4095', 'B', '3217']
Example Output:
9673