1. ## how many length-k strings can be made

A bit string is a list of 0s and 1s. How many length-k bit strings can be made?

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I was told the answer is k^2. Can someone explain this to me? I can see how this would work for when k=2.

(0,0) (0,1) (1,0) (1,1)

But, how can I know this will follow for larger numbers?

2. Originally Posted by absvalue
A bit string is a list of 0s and 1s. How many length-k bit strings can be made?
I was told the answer is k^2. Can someone explain this to me?
Actually that is incorrect.
The corect answer is $2^k$.
You have k positions. Each can be filled in two ways: 0 or 1.