Although most of these devices also have a decimal point, but this does not necessarily has to be connected. Devices can exist in common anode or common cathode types. The correct one depends on whether the decoder/driver circuits pull down (towards the negative supply rail) or pull up (towards the positive supply rail) to light a segment.
I hope this answers the question "How can we display the output?".
The reason for the conversion is to display numbers on a 7 segment display. However you can use anything that runs off of 5vdc that is often used to drive these circuits. You could use an ordinary led in series with a resistor. If you use arduinos, you can see the output on the output monitor. You could use a voltmeter to see if the proper outputs are on.