Fermented hydrometer (with Oechslescale) degrees divided by 8 = % volume of alcohol.

100 ml of dissolved sugar = 159 grammes (100:0.63)

900 ml water = 900 grammes

159
900
1059 grammes

This is 1059 grammes over 1 kg = +59 degrees on the hydrometer (with Oechslescale)

When the sugar has fermented to alcohol it looks like this:

100 ml alcohol x 0.8 = 80 grammes
900 ml water = 900 grammes

80
900
980 grammes.

This is 20 grammes under 1kg, i.e., minus 20 hydrometer (with Oechslescale) degrees (coloured field)