I want to make an LED display that can show 3 digits, so I have 7 segments for each digit for a total of 7x3=21 LEDs. I need this to display some data from a sensor I'm capturing with an Arduino, and I want to use the same Arduino to run the display. How can I do this without flickering the LEDs? The only way I could think of is to use 7 digital pins to display the digits 1 by 1 and just cycle through them very quickly. The problem is that this means the LEDs are off 2/3 of the time, and also they have to flicker which can't be good for the LEDs and the eyes (I'm speculating). Maybe there is some trick you can do, but I'm not familiar with electronics and I've thought about this for 4 days doing all sorts of designs with transistors and the bottom line is that I can't do it, it's like the hardest riddle ever. Any ideas?