Small 7-segment displays of about 0.5" height (like the one mentioned by papunblg) have a single LED in each segment and the maximum current rating is usually around 20mA per segment. Therefore the maximum when all segments are lit up is about 140mA. However, the actual current is controlled by external circuits. How much current is required depends on the application. For example, for indoor viewing in subdued lighting, 1 or 2mA per segment may be enough. Some viewing conditions may make it desireable to use the full 20mA.
Larger digits may use 2 or more LEDs in series in each segment, still with a maximum current rating of 20mA but at a higher voltage. Still larger displays may have a combination of series and parallel arrangements in each segment - e.g. 4 LEDs in series and 3 such strings in parallel, a total of 12 LEDs in each segment. Some have a smaller number of higher-powered LEDs.