some reason voltmeters have had scales like 0-3v, 0-30v, etc. for a long time. You might have expected 0-1v and 0-10v, etc. to be more common. However, that's not the way it is, and it probably won't change any time soon. That situation has led to some interesting ways to specify voltmeters.
If you had a voltmeter that had a 0-1v range, and it had ten bits, it would probably be designed to have a range from 0-1.024v, and it would measure voltages in steps of .001v. Then, the measurement results would be things like 0.314v or 0.582v, things like that. Displayed values would all have exactly three decimal places, and the instrument would be referred to as a 3 digit meter. If you use the same converter on a 0-10v scale (and put the voltage through a 0.1x voltage divider!), then the results would be things like 3.14v or 5.82v. You would get exactly the same number of significant figures, and you would still refer to the meter as a 3 digit meter.
Let's think about this situation.
If you have a voltmeter with a 0-1v scale that can read increments of .001v the meter is a 3 digit meter.
If you have a voltmeter with a 0-1v scale that can read increments of .0001v the meter is a 4 digit meter.
If you have a voltmeter with a 0-10v scale that can read increments of .001v the meter is a 4 digit meter.
If you have a voltmeter with a 0-100v scale that can read increments of .001v the meter is a 5 digit meter.