Number of subnets

Question

Finally what we have to do?

Number of subnets? 2^n -2  or 2^n, where n is the number of borrowed bits ?

Comments

2^n generally;

But it depends on you, how you are dividing the subnet.

There is a question in GATE, where 2^n was not matching with options, but 2^n-2.

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suppose if subnet bits =3 and question is to calculate total no of subnets and options include

a) 8

b) 6

in this situation wht we would choose?

Please reply .