How to calculate range of IP address given starting address and number of address required

Given a starting addre开发者_Python百科ss, say 192.16.0.0, How do I calculate the IP address ranges to allocate 4000, 2000, 4000 and 8000 IP addresses to 4 companies that have requested it (in that order).

Address range 192.16.16.0 to 192.16.23.255 is sufficient for this request or is over allocated or under allocated. Can anybody explain how to solve this?

You need 18000 addresses. 18000 > 2^14. So you need a /15 network at least. It looks like you have one /11 allocation. So it isn't enough.