20.4 hours
The answer is incalculable because hours is a unit of time and miles is a unit of distance. If you are asking how many hours it would take you to drive 306 miles, you would have to include how fast you are going.
640 miles would be 8 hours exactly. 639 is 7.9875
if you are driving then you would go about an avaerage of 60 miles per hour. if you were going this fast then going 281miles it would take you 4 hours and 41 minutes.
162.5 miles
It depends on how fast you are going.
2.3 hours
It would depend on how fast you're going--if you're going an average of 50 mph, then it would take approximately 26 hours for 1300 miles.
7 hours, 38 minutes, 46.15 seconds
It depends. If you were going 40 MPH (which seems reasonable), it would take 20 hours. If you were going 80 MPH, it would take 10 hours.
About 8.25.
Approximately 66.4 hours