Powers of Minus Ten, and yes it still exists - I do a little bit of maintenance to keep it alive because it's used by a bunch of schools. https://apps.apple.com/us/app/powers-of-minus-ten/id42912355...

I'm actually still working on something similar but, basically, no longer trying to run a business selling educational games (more, profits from commercial development contracts with actual budgets funding the cooler projects).

If they made it in 2010, without updates, it's no longer on the App store. Apple takes down things that don't get updates.

It's this: https://apps.apple.com/us/app/powers-of-minus-ten/id42912355...

(note: I am not OP)