The Raspberry Pi is a great low-cost computer chip designed for fiddling. The prices can start at $5, and go up to $55. The cheaper the computer, the lower RAM (or processor power).
As the new board, Raspberry Pi 4, is coming out, more ARM operating systems are becoming usable for the newer models.
Due to the arrival of the Raspberry Pi 4, Manjaro linux has released new OS editions.
First, go to Manjaro.org. Click 'TRY MANJARO', then, on the top navbar, click Editions > ARM > Raspberry Pi 4 > KDE Plasma
Now, download the .XZ and also have balenaEtcher downloaded and opened. Choose the XZ and flash the image. Manjaro is being installed, and pre-setup.
Once the setup is complete, insert the MicroSD card into your Pi 4 and turn it on. Manjaro linux will boot, and you can use the OS to it's full capacity.
'Enjoy the simplicity.'
You now have Manjaro LTS installed on your Pi! It should run fast, and it is recommended you setup a 'cluster computer' with multiple Pi's to go even faster.