The answer will depend on the degree to which the number is rounded. Without any indication of that, it is not possible to answer the question sensibly.
11.7 billion rounded to the nearest 10 billion would be 12 billion.
12, because if you rounded to the tenths spot you get 12
12
0.2708
12
12.0107 rounded to the nearest whole number is 12.
11.7 billion rounded to the nearest 10 billion would be 12 billion.
12, because if you rounded to the tenths spot you get 12
12 is an integer and so already rounded to a hundredths (and more).
12
12
Rounded to the nearest whole number it is 12
0.2708
sqrt(12) = ±3.4641 (rounded)
12
If rounded to a whole number, it would be rounded to 8.
12 if rounded to the nearest whole number