First you have to find out how many meters are in 1 km. You can look this up or just memorize that kilo means thousand so there are 1000 m in every km
1 km
2890km x ------------
1000m
Then multiply by putting the 2890km over 1.
2890m 1km
------------ x -------------
1 1000m
The meters units cancel and you get
2890km
--------
1000
You can either divide that on a calculator to get a decimal answer or you can reduce the fraction. The decimal answer is 2.89km
The improper fraction answer is 289/100 km and the mixed number answer is
2 and 89/100ths km
I am guessing you would want to go with the decimal answer in this case.