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.

[EX Q]: ['j', 'f', '3831', 'B', 'D']
[EX A]: 3831

[EX Q]: ['I', '7815']
[EX A]: 7815

[EX Q]: ['y', 'a', '2423', 'z', '381', 'n']
[EX A]:
2804