How many unique IP addresses could be made in a fixed-length IP address system using 6 bits? The answer is 64. But 6 bits is 2^5 which is 32 so why is it 64?

# U1 L9 - question on bit size

Hi @micannon,

Thanks for your question!

The 6th bit represents the number 32 - In other words, if you turn on just the 6th bit, you get the number 32.

100000 (binary) = 32 (decimal)

However, we get to use the rest of the bits too, and the largest number you can represent with 6 bits is found by turning on all the bits, which gives you 63.

111111 (binary) = 63 (decimal)

Including 0, thatâ€™s 64 unique combinations.

Hope that helps!

Frank