The Engineering Projects

Hello I trying a project with a rasp b+. I hope that I would be useful for the rasp zero, but I'm already in the develop time.
I just have a thermostat telegram controlled with WiFi. Not to much complex but enough for my interest. It takes a sensor value and decides if turn off or on a relay. So I need some gpio for this use. I would like to add a led matrix in order to show current temperature and humidity, but I'm in doubt about the gpios they need to work. I would need to show 2 number, a coma, another number and the Centigrades symbol or percent one.
How many gpios I would need?

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