how calculate the number of ip addresses in a range?

[Matthew D. Fuller]

On Thu, Aug 08, 2013 at 08:55:38AM -0700 I heard the voice of
Michael Sierchio, and lo! it spake thus:
>
> pkg_add -r ipsc

For another, there's a "cidrcalc" program installed by devel/libcidr
(full disclosure: of which I'm the author) that does similar things:

% cidrcalc -bs 10.80.128.35/27
  Address: 10.80.128.35
  Netmask: 255.255.255.224 (/27)
  BinAddr: 00001010 01010000 10000000 00100011
              10       80      128       35
  BinMask: 11111111 11111111 11111111 11100000
             255      255      255      224
 Wildcard: 0.0.0.31
  Network: 10.80.128.32/27
Broadcast: 10.80.128.63
    Hosts: 10.80.128.33 - 10.80.128.62
 NumHosts: 30
 Supernet: 10.80.128.0/26
  Subnets: 10.80.128.32/28
           10.80.128.48/28


-- 
Matthew Fuller     (MF4839)   |  fullermd at over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/
           On the Internet, nobody can hear you scream.