How much cinder is needed to spread a layer of cinder 4 cm thick on a rectangular ground with a length of 45 meters and a width of 29 meters?
在一块长45米、宽29米的长方形地上铺一层4厘米厚的煤渣，需要多少煤渣？
<gadget id="calculator">4 / 100</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">45 * 29 * (1/25)</gadget>
<output>261/5 = around 52.2</output>

<result>261/5 = around 52.2</result>