Question 435648
Hint: 1 kilo meter = 1000 meters (kilo = 1000 of whatever)
Don't look for or try to memorize a formula, make use of the units.
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eg:  5 km/sec = 5 km/sec * 1000 m/km 5*1000 km * meters/ km * sec = 5000 m/sec
Notice that the km cancels and leaves meters/sec
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If you do it "the wrong way", 5 km/sec / 1000 m/km = 5/1000 km*km/m*sec
= 0.005 km^2/m*sec ??? the units make no sense.
Use the units to confirm you made the correct conversion.