how calculate the number of ip addresses in a range?

[s m]

hello guys,

i have a question about ip addresses. i know my question is not related to
freebsd but i googled a lot and found nothing useful and don't know where i
should ask my question.

i want to know how can i calculate the number of ip addresses in a range?
for example if i have 192.0.0.1 192.100.255.254 with mask 8, how many ip
addresses are available in this range? is there any formula to calculate
the number of ip addresses for any range?

i'm confusing about it. please help me to clear my mind.
thanks in advance,
SAM