HGW is Wiesler's initals and xx7 was just his number.
Most likely its the serial number
15 percent 0 equals 0; 0 percent 15 equals 0. Both the above are true
yes
0
0
maybe
It equals 0.
It equals 0
x=0
0 it equals 0
For y - 2y - 3y equals 0, y equals 0.