How CIDR can be used to effectively manage the IP address space?

Using CIDR IP addressing, any number of contiguous bits can be assigned to identify networks, depending on the number of hosts it needs to support. This will greatly reduce the number of wasted IP addresses. For example, let us say a network has 900 hosts. If classful IP addressing is used, this network needs 4 class C IP addresses or one class B IP address. If a class B IP address is used, as the maximum number of hosts in a class B network is 65534, a very large number (65534 - 900) of host IP addresses will be wasted. As the number of class C IP networks is limited (2097152), it is not preferable to assign 4 class C IP addresses to this network. On the other hand, if CIDR is used, then this network can be assigned an IP address with a network prefix of 22 (i.e. /22). This means, 10 bits are available for hosts, resulting in 1024 available host IP addresses, satisfying the exact requirements of the network. So CIDR the IP address space can be effectively used.