At present, the global desertification land area has reached 36 million square kilometers, accounting for 1/4 of the total land area, and it is still expanding at a rate of 50,000 to 70,000 square kilometers (average 60,000 square kilometers) every year. Has become the "number one killer" of the global ecology. There are more than 110 countries in the world affected by deserts, and 1 billion people are directly threatened. If it is not stopped, how many years will there be no grass on the earth?
目前，全球荒漠化土地面积达到3600万平方千米，占陆地总面积的(1/4)，而且每年仍按5万至7万平方千米(平均6万平方千米)的速度扩展，土地荒漠化已成为全球生态的"头号杀手"．全世界受荒漠危害的国家达110多个，10亿人口受到直接威胁．如不制止，多少年后地球上连一根草都看不到了？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3_600 * (1/4)</gadget>
<output>900</output>

<gadget id="calculator">3_600 - 900</gadget>
<output>2_700</output>

<gadget id="calculator">2_700 / 6</gadget>
<output>450</output>

<result>450</result>