According to Wikipedia the Moon's mass is about 1.23% of Earth's but its gravity is 0.1654g, or 16.5%. If gravity is proportional to mass, why isn't the Moon's gravity 1.23% of Earth's?
EDIT: Presumably something like this applies:
Where, if the top circle is the moon and the bottom is the Earth, the particles closer to you apply more gravitational pull. Therefore whilst the further-away particles on Earth cause the gravity to be 6 times higher, they don't cause nearly as much gravitational pull as those close to you. With the Moon, all of its particles are close enough that they apply quite a lot of gravitational pull.