At the beginning of the year, manufacturing overhead for the year was estimated to be $250,860. At the end of the year, actual direct labor-hours for the year were 20,860 hours, the actual manufacturing overhead for the year was $245,860, and manufacturing overhead for the year was underapplied by $10,820. If the predetermined overhead rate is based on direct labor-hours, then the estimated direct labor-hours at the beginning of the year used in the predetermined overhead rate must have been?