3.1 may refer to:
* An approximation of the mathematical constant
* A shorthand reference to release 3.1 of some piece of software, such as
Windows 3.1
Windows 3.1 is a major release of Microsoft Windows. It was released to manufacturing on April 6, 1992, as a successor to Windows 3.0. Like its predecessors, the Windows 3.1 series run as a shell on top of MS-DOS; it was the last Windows 1 ...
* The estimated percentage of
2024 YRâ‚„ hitting Earth on December 22, 2032 since the date of February 18, 2025
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