What is the square centimeter area occupied by a square glass with a side length of 8.4 decimeters on a drawing with a scale of 1:20?
一块边长8.4分米的正方形玻璃，在比例尺1：20的图纸上占面积多少平方厘米．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">8.4 * 10 * (1/20) * 8.4 * 10 * (1/20)</gadget>
<output>17.64</output>

<result>17.64</result>