In the level 3 on rooms 3 you will see at the next table there wastebasket, zoom into the waste basket and press and take a long cardboard box and store it in your inventory menu.
Then go to the area of the window, you zoom the window and there was a knife in there and grab the knife. See the picture below
Press the cardboard box in your inventory twice to zoom into it, press the knife in your inventory and press it on the cardboard box to open it.
Then you go to the room with a chair and a lamp on it is empty, press the seat to be shifted to the center right under the lights.
Zoom in on the light and drag the light bulb in your inventory into the light fixture, and you will see the code for the door on the wall. Return to the front room door and enter the code (783461)and the door will be open level 3
Now continue to the 100 Rooms Beat Level 4 Explanation, or back to the 100 rooms beat level 2 solution