On a map with a scale of 1:100000, measure a rectangular piece of land with a length of 8 cm and a width of 5 cm. What is the actual area of this rectangular land?
在比例尺是1：100000的图上，量得一块长为8厘米，宽为5厘米的长方形地，这块长方形地的实际面积是多少？
<gadget id="calculator">1 / 100_000</gadget>
<output>1/100_000 = around 0.00001</output>

<gadget id="calculator">8 / (1/100_000) / 100</gadget>
<output>8_000</output>

<gadget id="calculator">1 * 10_000</gadget>
<output>10_000</output>

<gadget id="calculator">5 / (1/100_000) / 100 / 10_000</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">8_000 * (1/2)</gadget>
<output>4_000</output>

<result>4_000</result>