Texas Instruments has both apps free (normally $30 a piece) until 4/30 https://apps.apple.com/us/app/ti-nspire/id590823242 https://apps.apple.com/us/app/ti-nspire-cas/id545351700 GraphNCalc83 ($5.99) also free https://apps.apple.com/us/app/graphncalc83/id744882019