210=1024
1024
Considering that 5 are static.....take the remaining: 2^7 = 128
The question is exactly equivalent to: "What's the highest binary number with 6 bits ? There are 64, corresponding to the binary numbers from 0 to 63.
You are essentially asking how many different bit strings of length 9 are there, as the first 3 bits are fixed. The answer is 2^9 = 512.