3. (6 points) The average distance between the Earth and the Moon is approximately 384400000 meters. Rewrite this number using “billion” as the unit is $\qquad$ billion meters.
【Analysis】According to the method of rewriting integers, moving the decimal point of 384400000 to the left by 8 places will give the solution.
【Solution】Solution: $384400000=3.844$ hundred million.
Therefore, the answer is: 3.844.