Working with Cells and NotebooksMathematica notebooks consist of sequences of cells. The various kinds of cells are listed in Format  Style. To create a new cell:- Move the pointer in the notebook window until it becomes a horizontal I-beam.
- Click, and a cell insertion bar will appear; start typing. By default, new cells are Mathematica input cells.
To create a new cell to hold ordinary text:- Click in the notebook to get a cell insertion bar.
- Choose Format Style Text.
- or - - When you start typing, a text cell bracket appears.
To change the style of a cell:- Click the cell bracket. The bracket is highlighted.
- Select a style from the Style submenu. The cell will immediately reflect the change.
TIP
 Choose Format Show ToolBar to get a toolbar at the top of the notebook. To close a group of cells:Double-click the outermost cell bracket of the group. When a group is closed, only the first cell in the group is displayed, and the group bracket is shown with a triangular flag at the bottom. To open a group of cells:Double-click a closed group's cell bracket. To print a notebook:Choose File Print. The notebook style will be automatically optimized for printing. To change the overall look of a notebook:- Choose Format Style Sheet.
- Choose a style sheet. All cells in the notebook will change appearance, based on the definitions in the new style sheet.
TIPS
Mathematica comes with a collection of color and black-and-white style sheets.
Use Format Edit Style Sheet to set up individual style sheets for Mathematica notebooks.
Changes to a notebook that only involve opening or closing cell groups will not cause the front end to ask you if you want to save such changes when you close the notebook before saving. To save these changes, use File Save before you close the notebook or quit Mathematica.
To close a notebook, click the Close button in the title bar. You will be prompted to save any unsaved changes.
Windows: To close notebooks without being prompted to save, hold down the  key when clicking the Close button. For more information
Notebooks: The Mathematica Book, Sections 1.3.4 and 1.3.5.
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