Translation of "3" into Japanese

In fact, an artist lacking in confidence and fortitude would lose focus after 2 or 3 hours.

さしずめ忍耐力に自信のない筆者などは、2,3時間で音をあげてしまう作業である。

The doors of the train on line 3 are closing. Please be careful.

三番線、ドアが閉まります。ご注意下さい。