I'm not sure how to explain the full details about it.
Note the most left buttons starting from the top are: 1,2,4,8,16
The buttons below and to the right are : 1,2,4,8
The button close to the center is a input carry.
you can turn on bit 1 and second bit 1 this will add up to a value 2
You can have any of them on and you will get the hex value displayed on the right side.
