172.16.16.0
is the network address.
255.255.240.0 -> 8 bits (from last octet) + [ 255 - 240 = ( 15 => 1 + 2 + 4 + 8 ) ] I'll take 4 bits "borrow" from third octet = have total 12 bits for hosts!
Thus: 32 bits - 12 bits = /20 VLSM with 4094 hosts can be subnetting in 16 subnets
