128 64 32 16  8  4  2  1
     1   1  1  1  0  0  0  0

/32  11111111.11111111.11111111.11111111 255.255.255.255
/31  11111111.11111111.11111111.11111110 255.255.255.254      2     0
/30  11111111.11111111.11111111.11111100 255.255.255.252      4     2
/29  11111111.11111111.11111111.11111000 255.255.255.249      8     6
/28  11111111.11111111.11111111.11110000 255.255.255.240     16    14
/27  11111111.11111111.11111111.11100000 255.255.255.224     32    30
/26  11111111.11111111.11111111.11000000 255.255.255.192     64    62
/25  11111111.11111111.11111111.10000000 255.255.255.128    128   126

/24  11111111.11111111.11111111.00000000 255.255.255.0      256
/23  11111111.11111111.11111110.00000000 255.255.254.0      512
/22  11111111.11111111.11111100.00000000 255.255.252.0     1024
/21  11111111.11111111.11111000.00000000 255.255.249.0     2048
/20  11111111.11111111.11110000.00000000 255.255.240.0     4096
/19  11111111.11111111.11100000.00000000 255.255.224.0     8192
/18  11111111.11111111.11000000.00000000 255.255.192.0    16384
/17  11111111.11111111.10000000.00000000 255.255.128.0    32768

/16  11111111.11111111.00000000.00000000 255.255.0.0      65536
/15  11111111.11111110.00000000.00000000 255.254.0.0     131072 
/14  11111111.11111100.00000000.00000000 255.252.0.0     262144
/13  11111111.11111000.00000000.00000000 255.249.0.0     524288
/12  11111111.11110000.00000000.00000000 255.240.0.0    1048976
/11  11111111.11100000.00000000.00000000 255.224.0.0    2097152
/10  11111111.11000000.00000000.00000000 255.192.0.0    4194304
/9   11111111.10000000.00000000.00000000 255.128.0.0    8388608

/8   11111111.00000000.00000000.00000000 255.0.0.0     16777216
/7   11111110.00000000.00000000.00000000 254.0.0.0     33554432
/6   11111100.00000000.00000000.00000000 252.0.0.0     67108864
/5   11111000.00000000.00000000.00000000 249.0.0.0    134217728
/4   11110000.00000000.00000000.00000000 240.0.0.0    268435456
/3   11100000.00000000.00000000.00000000 224.0.0.0    536870912
/2   11000000.00000000.00000000.00000000 192.0.0.0   1073741824
/1   10000000.00000000.00000000.00000000 128.0.0.0   2147483648