TASK DEFINITION: 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.
PROBLEM: ['D', '1259', '8927', '3345', '553', '7209', '2507', 'l', 'o', '7317', '1227', '6749', 'S', '3171', 'I', '197', '9577', 'j', 'Q']

SOLUTION: 52038

PROBLEM: ['w', '2281', '8651', '2203', 'q', 'n', '4253']

SOLUTION: 17388

PROBLEM: ['4515', '3911', 'M', 'T', 'w', 'F']

SOLUTION:
8426