What are the locks real estate sellers use to lock up to house?

my friend got one of thoes and we were trying to find out the code cause someone gave it to her and said try to get it open and i was wondering what they were called i thought it was a padlock is is like a caculator but it is a lock and real estate users use it to lock up the house and we were looking on youtube how to open it by ear paperclips anything please help