Use the terminal or command line to find the Scala version on various operating systems (OS). This is how to do it on different OS:

In Windows:

1. By pressing Win + R, inputting cmd, then clicking Enter, you may launch the command prompt.
2. Enter the scala -version after typing it.
3. It will show the version of Scala that is installed on your machine.

On macOS:

1. Go to Applications > Utilities > Terminal to open the Terminal.
2. Enter the scala -version after typing it.
3. It will show the version of Scala that is installed on your machine.

On Linux:

1. Get a terminal window open.
2. Enter scala -version after typing it.
3. It will show the version of Scala that is installed on your machine.

Additionally, you may use an IDE (Integrated Development Environment) like Eclipse or IntelliJ IDEA, or a Scala REPL (Read-Eval-Print Loop), to programmatically verify the version of Scala.

For example, in the Scala REPL:

scala> util.Properties.versionString
res0: String = version 2.13.8