A 6-meter-deep cylindrical pool is filled with water, and 15 cubic meters of water is used every day. After 15 days, the water depth is measured to be 4.5 meters. If you want to make an iron sheet cover for the mouth of this pool, how many square meters of iron sheet should be used at least?
一个6米深的圆柱形的水池装满了水，每天都要用去15立方米的水，15天后再测量水深是4.5米．如果要给这个水池口制一个铁皮盖子，至少要用铁皮多少平方米？
<gadget id="calculator">6 - 4.5</gadget>
<output>1.5</output>

<gadget id="calculator">15 / 1.5</gadget>
<output>10</output>

<gadget id="calculator">15 * 10</gadget>
<output>150</output>

<result>150</result>