A paragraph could very well be one sentence, but it could just as easily be a long 20 sentence paragraph. It's usually thought of as being a complete separate thought and containing as many sentences are needed before you reach a natural breaking point to move on to the next paragraph. Hope that helped.
Centi-means one-hundredth, so 1metre = 100 centimeters, therefore 1 decameter = 10 x (100 centimeters) = 1000 centimeters. Hecto-means one hundred, therefore 1 hectometer = 100 meters = 10 decameters. Kilo-means one thousand, of course, so 1 kilometer = 1000 meters, and since 1 hectometer = 100 meters, 1 kilometer = 10 hectometers.
High Earth orbit (HEO) is any orbit higher than geostationary orbit at 35,786 km (22,236 mi), which has over 400 active satellites. 'Geocentric orbit' is the term for an orbit around Earth. 'Heliocentric orbit' is a term for an orbit of the Sun. 'Areocentric orbit' is the term for an orbit of Mars.