Question

Superfly, mass of only 1 gram, but capable of flying 840 million km/hr. meets a locomotive with a mass of 20,000 kg, traveling 40 km/hr. Who has the greater momentum?

I know I need to convert mass to kg and covert momentum in Kg-Km/hr. I just don't know how. Please help.
bobpursley
I would convert 20,000 km to grams.
2E4kg=2E7grams

momentum locomoative=2E7*40 gKm/hr
momentum fly= 1*8.40E8 gkm/hr

momentum locomotive=8E8 gkm/hr
momentum fly=8.4E8 gkm/hr