Wawa:
Not sure what you mean, but an Uno has a 10-bit A/D which means 2^10= 1024 steps.
So if you design your voltmeter (resistor divider and code) right, then you only have 1024 display steps.A "9.999" display would need 10000 steps. That's 10 times more than what you have.
A "50 volt" voltmeter would only have 1024/50= ~20 steps per volt.
ONE decimal place (10 steps per volt) would be ok, two or more decimal places would be impossible.
Leo..
[/quote
Thank you very much Leo,
10 bit is quite sufficient for me, 3 digit is okay as in my first line.