Found this incredible function on my Fx991EX if you press shift and Option button on left corner it creates a QR code that can be scanned with a phone to see graphing
Casio FX991EX-Classwiz | Mathematics, Learning and Technology
Casio fx-991EX classWiz user manual and commands.
CASIO Calculadoras
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Casio fx-991EX classWiz user manual and commands.
Casio fx-991EX classWiz user manual and commands.
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Casio fx-991EX classWiz user manual and commands.
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Casio fx-991EX classWiz user manual and commands.
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Casio FX-991ES PLUS - Calculadora científica (417 funciones, 15 + 10 + 2 dígitos, pantalla Natural), color gris : Amazon.es: Oficina y papelería