A trapezoidal rice field has an upper base of 68 meters, a lower base of 112 meters, and a height of 45 meters. The average harvested rice per square meter is 0.2 kilograms. How many tons of rice are harvested in total?
一块梯形稻田，上底68米，下底112米，高45米，平均每平方米收水稻0.2千克，一共收水稻多少吨？
<gadget id="calculator">112 + 68</gadget>
<output>180</output>

<gadget id="calculator">45 / 2</gadget>
<output>45/2 = around 22.5</output>

<gadget id="calculator">0.2 / 1_000</gadget>
<output>0.0002</output>

<gadget id="calculator">180 * (45/2) * 0.0002</gadget>
<output>0.81</output>

<result>0.81</result>