192.168.25.0/24   (the subnet mask contains 24 ones and 8 zeros at the end)

192.168.25.4   AND
255.255.255.0				
-------------
192.168.25.0   network address, the first in the interval of IPs

32 - 24 = 8

2 ^ 8 = 256   IPs in the interval, which is:

192.168.25.0 - 192.168.25.255

------------------------------------------

192.168.25.0/28		(the subnet mask contains 28 ones and 4 zeros at the end)

192.168.25.4      AND
255.255.255.240
-------------
192.168.25.0   network address, the first in the interval of IPs

32 - 28 = 4

2 ^ 4 = 16   IPs in the interval, wgich is:

192.168.25.0 - 192.168.25.15

------------------------------------------

192.168.25.17/28

192.168.25.17      AND
255.255.255.240
-------------
192.168.25.16   network address, the first in the interval of IPs

17 = 10001     so  17 AND 240 = 16

32 - 28 = 4

2 ^ 4 = 16   IPs in the interval, which is:

192.168.25.16 - 192.168.25.31