Edit - Select All

Ribbon bar. Select the Edit tab. In the Clipboard/Data group, click Select All to select the entire spreadsheet.

Classic menus. From the Edit menu, select Select All (or press CTRL+A) to select the entire spreadsheet.

You can also select the entire spreadsheet by clicking in the lower half of the Info Box (if you click in the upper-left corner of the Info Box, the entire Info Box is selected). See also: Spreadsheet Window Overview and Spreadsheet (Multimedia Table) Overview.