There is a square lawn with a side length of 30 meters on the campus. If each square meter of lawn requires 4 kg of water per day for maintenance. How many tons of water does this lawn use per day?
校园里有一块边长30米的正方形草坪，如果每平方米草坪每天要4千克水进行养护．这块草坪每天用水多少吨？
<gadget id="calculator">4 / 1_000</gadget>
<output>1/250 = around 0.004</output>

<gadget id="calculator">30 * 30 * (1/250)</gadget>
<output>18/5 = around 3.6</output>

<result>18/5 = around 3.6</result>