A coworker wanted to run two separate copies of Slack on the Mac, so that he could watch updates from two different Teams at the same time. Personally, I just use the native multi-Team support in the app, but I can see how this would be useful. One answer is to use this command from the Terminal:
open -n /Applications/Slack.app
Scottish mathematicians are cool. Also, this led me to look up Lattice Multiplication, which is being taught in Common Core. But I think the Genaille-Lucas rulers were probably the coolest bit. Pre-calculate smaller pieces of a multiplication/division problem, use a little modulus magic, and large problems become a breeze.
Bone Up on Your Multiplication Skills | Hackaday
TL;DR: If you use the php-ssh2 extension for your WordPress core / theme / plugin updates, you might want to wait a little longer before upgrading to PHP 7.