1# the earth is two times/half/200 percent/ 3 quarter/one third as big as the moon.
2# the earth is two times/half the size of the moon.
3#the earth is 200 percent/ 3 quarter/one third of the size of the moon.
i know 1# and 2# are OK. although #3 has the same meaning, i am not sure whether of is neccessary there.