F=d2Gm1m2
where F is the force on a particle on the surface of Mars, m1 is the mass of Mars, m2 is the mass of the particle and d is the radius of Mars.
As F=m2a where a is the acceleration of the particle on Mars,
a=d2Gm1
As G=6.6710−11 kg-1m3s-2 we get
a=3.4106m26.6710−11 kg-1m3s-2 6.421023kg=1.732106.677.38ms−2=1.64ms−2