[{"_id":1,tin:"34.545.646/4245-24"},{"_id":2,tin:"34,545,646/424524"},{"_id":3,tin:"34545646/4245-24"},{"_id":4,tin:"24545646/4245-24"},{"_id":5,tin:"34545646/4245-25"}]

db.collection.find({"$expr":{"$eq":[/** "filtered" number string goes here*/"34545646424524",{/** strip everything except digits from tin*/"$reduce":{"input":{"$range":[0,{"$strLenCP":"$tin"}]},"initialValue":"","in":{"$let":{"vars":{"char":{"$substrCP":["$tin","$$this",1]}},"in":{"$cond":[{"$regexMatch":{"input":"$$char","regex":"\\d"}},{"$concat":["$$value","$$char"]},"$$value"]}}}}}]}})