Thank you :)
Firstly I calculated the 5x smaller gravity ( g/5 ) which resulted in 1,962 m/s^2
Then I converted the 6370km to meters ( 6 370 000 m )
Then, using my approach sqrt( 1,962 x 6370000 ) / ( 6,67 x 10^-11 x 6x10^24 ) i ended up with sqrt 18383940 / 40,02 x 10^23 which ended up as...