As a double roll of wall paper is usually 16 yards long, the number of strips a roll will cut can be found by dividing 16 yards by the length of one strip. The length of a strip is obtained by measuring the height of the room from the top of the base-board to the ceiling. Be sure to divide 16 yards by the length of one strip in _yards_, or else to divide its equivalent, 48 feet, by the length of one strip in _feet_. If a room is not already papered the number of full length strips may be found by measuring the distance round the room, exclusive of the distance across doors and windows, and dividing it by the width of the paper. One must then measure spaces too short or too narrow for whole strips and as before calculate how many full-length strips they amount to. When the number of full-length strips required for a room has been obtained by either of the foregoing methods, the number of _rolls_ required may be obtained by dividing the number of strips needed by the number of strips a roll will cut. It is always wiser to get one roll more than the number thus obtained; this allows for the waste in matching and for strips which may be spoiled in the putting up. When the old paper has been examined remove it. Brush it over with hot water and peel it off. Sweep the walls and fill cracks and holes with plaster of Paris wet with water. Cut the margin from one side of each roll of paper, from the same side in every case. Usually the margin is wider on one side than on the other, which helps one to remember which side to cut. Paper hangers cut off both margins but it is better not to do this until one has acquired some skill in paper hanging. As you unroll the paper to trim off the margin, also roll up again the part which has been trimmed. On a pasting board or on the floor run out enough paper, face up, from a trimmed roll to make a full-length strip. Make a fold in the paper at the length required and cut it with scissors or a sharp knife. Lay something across the ends to keep the strip from rolling up. Again run out paper from the roll about the length of the strip but this time lay it with the trimmed edge on the untrimmed edge of the strip and if necessary draw it up to make the pattern match. Cut off the few inches which have to be drawn beyond the strip to make the match, then cut a strip from the roll the length of the first strip. Continue to do this again and again until there are as many strips as you need. Then turn them all face down. Paste each strip with quick long strokes, using a wide paint brush or whitewash brush. Fold the lower end lightly toward the middle, far enough to keep it from touching the floor when you raise the strip by the upper corners. Place these corners against the wall where they belong and press the upper part of the strip against the wall, then brush it lightly downward with a clean brush, unfolding the lower part when you come to it.