import re
s = """Model Number : 123
Serial Number : 456"""
model_number = re.findall(r'Model Number\s*:\s*(\d+)',s)
print(model_number)
aW1wb3J0IHJlCnMgPSAiIiJNb2RlbCBOdW1iZXIgOiAxMjMKICAgICAgICAgICAgU2VyaWFsIE51bWJlciA6IDQ1NiIiIgptb2RlbF9udW1iZXIgPSByZS5maW5kYWxsKHInTW9kZWwgTnVtYmVyXHMqOlxzKihcZCspJyxzKQpwcmludChtb2RlbF9udW1iZXIp