import re
pattern = r"[0-9]\s*(?:[+-][+-]|\*/)\s*[0-9]"
strings = [
	'This is test 1 -- 1',
	'This is test 2',
	'This is test 3+1',
	'This is test 4 */4'
	]
 
for s in strings:
	res = re.search(pattern, s)
	if not res:
		print("Valid: " + s)	
 
 
 
				aW1wb3J0IHJlCnBhdHRlcm4gPSByIlswLTldXHMqKD86WystXVsrLV18XCovKVxzKlswLTldIgpzdHJpbmdzID0gWwoJJ1RoaXMgaXMgdGVzdCAxIC0tIDEnLAoJJ1RoaXMgaXMgdGVzdCAyJywKCSdUaGlzIGlzIHRlc3QgMysxJywKCSdUaGlzIGlzIHRlc3QgNCAqLzQnCgldCgkKZm9yIHMgaW4gc3RyaW5nczoKCXJlcyA9IHJlLnNlYXJjaChwYXR0ZXJuLCBzKQoJaWYgbm90IHJlczoKCQlwcmludCgiVmFsaWQ6ICIgKyBzKQkKCgo=