According to statistics, 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 about 60,000 square kilometers every year. If it is not stopped, how many years later will not even a blade of grass be seen on the earth?
据统计，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)，而且每年仍以约6万平方千米的速度扩展．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>14_400</output>

<gadget id="calculator">14_400 - 3_600</gadget>
<output>10_800</output>

<gadget id="calculator">10_800 / 6</gadget>
<output>1_800</output>

<result>1_800</result>