Does a King (Eastern King) Bed Fit in a 9 by 10 foot Room?

Yes. The bed with its frame takes about 82 by 86 inches, leaving 13 inches on each side and 34 inches at the foot in a 9 by 10 foot room. Very tight. Under 24 inches on the narrowest side means turning sideways to pass.

Convention puts the minimum at about 24 inches, which is enough to turn sideways and pass. Thirty inches is comfortable and lets a nightstand drawer open. Thirty-six inches is what a main walkway through a room wants. These are guidelines rather than a code requirement, so treat them as a target and not a rule.

Yes, and it is the most common measuring mistake. Most frames add 2 to 4 inches of rail on each side, so a bed is typically 4 to 8 inches wider and longer than its mattress. Upholstered and storage frames sit at the wide end. Always measure the frame dimensions the manufacturer publishes, not the mattress size.

You can, and it saves the clearance on that side entirely. The tradeoff is that whoever sleeps on the wall side has to climb over to get out, and making the bed becomes awkward. It works well for a single sleeper or a child, and poorly for two adults who get up at different times.