Answer is 4.
IP Address 130.56.0.0/16 indicates Network portion of 16 bits.
Since we need 1024=2^10 subnets so the subnet portion will be 10 bits.These subnet bits will be borrowed from the remaining 16 bits after the Network portion.
Now in the last subnet,All subnet bits will be 1 since subnet bits start from all 0’s to all 1’s.
First Address of last subnet will contain all 0’s in host portion:
130.56.1 1 1 1 1 1 1 1.1 1 0 0 0 0 0 0 which is 130.56.255.192.
Subnet bits Host bits
and Last Address of last subnet will contain all 1’s in host portion:
130.56.1 1 1 1 1 1 1 1.1 1 1 1 1 1 1 1 which is 130.56.255.255.
Subnet bits Host bits