Type hash key when using UK Mac/Apple keyboard on Ubuntu 21.04

Step 1: Configure keyboard layout

Under Settings -> Language and Region -> Input Sources, ensure the only configured input source is “English (UK, Macintosh)”

Step 2: Learn to go right

To type a hash (#): right-hand alt + 3.

I’m used to macOS, where the combination is left-hand alt + 3. It took me an embarrassingly long time to find out how to do this on Ubuntu.