To build a swimming pool with a length of 20 meters, a width of 15 meters, and a depth of 1.5 meters, if square tiles with an area of 5 square decimeters are used to paste the four walls and the bottom surface, can you help me figure out how many such tiles are needed at least?
修一个长20米，宽15米，深1.5米的游泳池，若用面积为5平方分米的正方形瓷砖贴四壁和底面，你帮忙算一下至少需要多少块这样的瓷砖？
<gadget id="calculator">20 * 1.5</gadget>
<output>30</output>

<gadget id="calculator">15 * 1.5</gadget>
<output>22.5</output>

<gadget id="calculator">30 + 22.5</gadget>
<output>52.5</output>

<gadget id="calculator">52.5 * 2</gadget>
<output>105</output>

<gadget id="calculator">15 * 20</gadget>
<output>300</output>

<gadget id="calculator">105 + 300</gadget>
<output>405</output>

<gadget id="calculator">405 / 0.05</gadget>
<output>8_100</output>

<result>8_100</result>