The land area of the earth is 149 million square kilometers, which is 212 million square kilometers less than the ocean area. How many billion square kilometers is the earth's surface area?
地球中的陆地面积是1.49亿平方千米，比海洋面积少2.12亿平方千米．地球表面积有多少亿平方千米？
<gadget id="calculator">1.49 + 2.12 + 1.49</gadget>
<output>5.1</output>

<result>5.1</result>