How to Find OS Build Number of Windows 10 Mobile Phone
Software (ex: "Windows 10 Mobile") indicates the general product name Microsoft uses to describe the release. OS build (ex: "10.0.10586.71") indicates the specific version build number of the release.
This tutorial will show you how to find the OS build number on your Windows 10 Mobile phone.
1. Open Settings, and tap on the System icon. (see screenshot below)
2. Tap on About. (see screenshot below)
3. Tap on More info. (see screenshot below)
4. You will now see the OS build number of your Windows 10 Mobile phone. (see screenshot below)
5. If you like, tap on the Start button at the bottom of your phone to go back to your Start screen. (see screenshot below)