[dwheeler]

That's version I learned as a kid. You might enjoy this page of mine:

The Definitive Four Fours Answer Key https://dwheeler.com/fourfours/

[floodle]

I love this:

> Note that these are large files; both are over 1.6 Megabytes, so don’t load these if you have a slow Internet connection

Just shows how far internet speeds have come...