If “Knights of the Round” was ever used, it was a long time ago and has disappeared. The few occurrences of "knights of the round" in Google Books that don’t follow with “table” seem to be digitisation issues (e.g. gifs for comms in google isotope and such etc.) “Tdble” or a hyphenated ta/ble.

Knights of the round,Knights of the round table http://ngrams.googlelabs.com/chart? Content=Knights%20of%20the%20round%2Cknights%20of%20the%20round%20table%2CKnights%20of%20the%20Round%2CKnights%20of%20the%20Round%20Table&corpus=0&smoothing=3&year_start=1800&year_end=2000

I can confirm that the round table was already a table in the earliest known text, or

For a question that is grammaticalally interesting, I don’t think this one is grammaticalal.

How much more time do you spend

online?
I will simply sit on the computer for ten minutes. — If I only intend to do a dozen things, I am going to be offline for a couple of minutes.

The time can be a direct complement of the verb stay, it requires a preposition.

How much time do you plan to live online?

What are my goals for online time next year

(where should I spend my time?)?
I spent 10 minutes online. I am going to use it ten times at least.

If you use “how much longer” instead of “how much more time”, then you don’t need the preposition, because long works on its own as an indication of time.

How much longer do you stick to online?
I can stay online long enough. Let you know what you are doing?

How much longer do you stay online?

“In a mathematical context, the word was exact.” “An exact calculation always gives the mathematically expected result.” “If you approximate, you get a result that looks similar, but also a bit closer.” “A circle of radius 1 is exactly 2, which is approximately 6.283. The circumference of this circle is 2, which is approximately 790.” “For instance, financial math calculations are usually done with exact arithmetic (using integers or fixed-point decimal numbers, with well-defined rounding rules), whereas physical math is usually done with inexact or approximate arithmetic (using floating point numbers, with rounding rules intended to maximize the precision of the result but not always to be perfectly reproducible).” “Strictly speaking, a physical measurement cannot be exact (the height of a stick has no end decimal place).” “Notwithstanding the use of the word exactly, the precision of measurement is so great that the uncertainty about the measured quantity can never be ignored. As such, you can still use the term exact to mean that the precision of measurement is so great that the uncertainty about the measured quantity will never matter.” “You can also use perfectly accurate in this context (again, meaning so accurate that any inaccuracy is irrelevant).”