This is basic knowledge. Of course one should know how many bits go in a byte. It's like asking if one should know how to replace a bulb. Not a software develop

This is basic knowledge. Of course one should know how many bits go in a byte. It's like asking if one should know how to replace a bulb. Not a software developer, every person should know that. It's like knowing that there're 1024 bytes in kibibyte or 1000 meters in kilometer. These days one should even know how exactly double is represented in hardware as it's the main type in JS and one should clearly understand bounds of integer numbers which could be represented in double without precision lost.