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.

['6731', 'f', '4561', '5601', 'i']
16893

['L', 'w', '2783', '6993', 'd', '9173']
18949

['6411', '2963', 'j', '8521', 'Y', 'N', '9489', '9739', '4649', '9785', '9647', 'R']

61204