Screen with calculator etc

How do I get the screen with calculator etc to show without a Mac mouse?

The same way you do with a Mac mouse. Open the Calculator app from the Applications folder.

Or, you can add Calculator to the Dock to make it more handy.

How do you open other Applications? It's the same process to open the Calculator application.

How do I get the screen with calculator etc

Are you possibly referring to the Dashboard? It is also an App, but you can configure Mission Control to open the Dashboard using a mouse button. I don't use a Mouse, so I cannot bring up a picture of the Mission Control screen with Mouse options. You can set it to show the Dashboard with a keyboard key:

Open Mission Control System preferences:

Set Show Dashboard to a function key (with or without modifier keys), or to the right should be options to configure a mouse button press (if supported).

You could create a keyboard shortcut that opens the Calculator app.

1. Open Automator
2. When asked the type of document, choose Service
3. From the left column, select Utilities
4. From the column next to the one on the left, select Launch Application and drag it over the box on the right side of the screen.
5. At the top, select Service receives: no input - select in: any application
6. Select the Calculator app from the drop-down menu beneath "Launch Application"
7. Close the window by clicking the red cross button in the upper left corner of the window. When prompted for the service name, give it any name that you want.
8. Go to System Preferences > Keyboard > Shortcuts and select Services in the box on the left. Under General, you should see the name you named the service we created a little ago.
9. Click on Add Shortcut and type a shortcut you like that is not already being used, like for example ctrl-⌥-⌘-L

Various methods are there to open an app , can use spotlight , type calculator in it and click on enter key .

Right click on the app can choose from three options keep in dock , open at login , show in finder .

You could ask Siri to open the Calculator app. It’s in Applications.

If the application is already open, try command - tab.