Have you any tracks for me to follow to be able to display a number (8 digits, from a computer or a Arduino card with a Keyboard) on a mini LCD (wire or wireless) and being able to take that lcd away with me?
You're dragging this display on an arduino with a wire for how much distance? and why?
Paint us a complete picture of what you want to do so we can help you better. Maybe you don't need to drag the display but instead have a wire between arduino and a sensor but anyway, some details are needed here.
I need to take the display with me without anything else.
It is just the same as the supermarket intelligent labels.
I need to program a message on a display and then disconnect that display and take it away with me. That display has to show the message enven taken apart from its base.
OK, your display needs to have an on board power supply as the display will clear when removed from arduino and power. Maybe 4 AAA batteries with low-drop-out voltage regulator on an LCD shield. I've no idea who sells such thing though.
There are also eInk displays becoming available - set them and then they stay that way until told otherwise (as I understand it). They are a bit rudimentary at the moment, but that might be a way forward.