NUMBERS file format
Files with the .numbers extension can only be created in the Apple Mac Numbers spreadsheet program. The Number program is to the Mac OS X iWork suite what Microsoft Excel is to the Windows Office Suite. The Numbers program allows users to create spreadsheets, tables, and use advanced formulas to calculate data values. NUMBERS spreadsheets can also contain graphs, tables, images, and other media types. Numbers files are quite similar to Microsoft Excel files in many wise, but they cannot be opened in Excel or LibreOffice Calc due to their proprietary and different structures.
A .number file is a compressed ZIP file comprised of several other different filetypes combined to make a NUMBERS file. The type of constituent files found in a .numbers file is dependent on the media type represented in the spreadsheet. Apple Inc.'s latest release of the Numbers program saves spreadsheets with a file folder containing the proprietary IWA format, .plist files, and .jpg screenshots that allow users to preview the document. Like other proprietary Office programs like Microsoft Office, the .numbers spreadsheet file type suffers from a lack of compatibility with other popular spreadsheet programs.