About ADXL357 output

I use the ADXL357 and just wan to get the Z-Axis's data.(Based on  the TI CC3200 to develop it.)

The question is, I found that the output is 20 bits in total(fig.1),

but the range of output data just between 47,104~55,296(about 16 or 17 bits)

so this problem limited the data processing.

I want to know the relations bewteen the data range(47,104~55,296) and the '20 bits',

and if possible, please tell me how they exchange and convert.



                                        fig.2                                                                                                    fig.3

*The words in the fig.3 are 'X-Axis, Y-Axis, and Z-Axis Sensitivity ±10 g 47,104 51,200 55,296 LSB/g'

*The images are from the datasheet about ADXL357