The speed of light is = 3x10^8 m/s. How long w ill it take to reach Pluto, 278,000,000,000 km away?

This is how I solved it:
3x10^8m/s x 1km/1000m x 1/2.78x10^11 km
I keep getting the wrong answer. I am not sure if this is how you set this conversion??

278,000,000,000 km = 2.78E11 km

Convert to m. 2.78E11km x (1000 m/km) = 2.78E14 m.
Then distance = rate x time
2.78E14 = 3E8 x time. Solve for time.
Your convertsion from 3E8m/s to km/s looks ok but then it should be 2.78E11/3E5 which is the same thing as
2.78E14/3E8. Approximately 1E6 seconds.