Reading integers from a file; the problem may be the newline characters

[menator01]

Someone correct me if I'm wrong but, you're testing for an integer in a string.

#! /usr/bin/env python3

with open('num.txt', 'r') as lines:
    lines = lines.readlines()
    print(list(map(str, lines)))
    for line in lines:
        print(line.strip())

Output:
['10 23 100 9 2\n', '15 63 9 13 55\n', '8 0 69 20 22 9\n', '10 25 33 42 5 8\n']
10 23 100 9 2
15 63 9 13 55
8 0 69 20 22 9
10 25 33 42 5 8