7-segment LED display max current
You kind of answered your own question: the datasheet states max per segment.

Is your 4-digit display direct-drive or multiplexed? If it is multplexed the max total current will be for one digit only. If it isn't, then it's max current per segment * #segments * #digits, which can be a lot for a big display as you can see.

Multiplexing the digits helps reduce the current since you light up only one digit at a time. You can use this technique even for a non-multiplexed display.

You can also use PWM techniques to manage the LED drive to achieve good brightness with less power. 

The tradeoff of multiplexing and PWM is in increased electromagnetic noise due to the switching activity, which you need to manage at the system level.

Finally, you need to consider not driving at max current. You can get very good brightness at even 1/4 the max or so, especially if the LEDs are high-efficiency.