Final answer:
To convert a number between 21 and 31 to binary, we follow a step-by-step process. In this case, the binary representation of 31 is 11111.
Step-by-step explanation:
To convert a number between 21 and 31 into binary, we start by determining the highest power of 2 that is less than or equal to the given number. In this case, the highest power of 2 that is less than or equal to 31 is 2^4, which is 16. We can write 31 as 16+15. Next, we write the binary representation of 16, which is 10000.
Then, we move to the remainder, which is 15. We need to find the highest power of 2 that is less than or equal to 15. The highest power of 2 is 2^3, which is 8. We can write 15 as 8+7. We write the binary representation of 8, which is 1000.
Finally, we move to the remainder, which is 7. The highest power of 2 that is less than or equal to 7 is 2^2, which is 4. We can write 7 as 4+3. We write the binary representation of 4, which is 100.
Therefore, the binary representation of 31 is 11111.