The earth's surface area is 510 million square kilometers, of which the ocean area is 301 million square kilometers, and the rest is land area. How many billion square kilometers is the land area less than the ocean area?
地球表面积是5.1亿平方公里，其中海洋面积是3.01亿平方公里，其余是陆地面积，陆地面积比海洋面积少多少亿平方公里？
<gadget id="calculator">5.1 - 3.01</gadget>
<output>2.09</output>

<gadget id="calculator">3.01 - 2.09</gadget>
<output>0.92</output>

<result>0.92</result>