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.
['8039', '265', '8885', '6791', '9809', 'T', 'd', '8611', 'h', 'o', '8545', 'U', '4321', '3671', 'd', '9673', 'b', 'R', 'K']