On a drawing with a scale of 1:400, measure the length of the rectangle to be 4cm and the width to be 3cm. What is the actual area of the rectangle?
在比例尺是1：400的图纸上，量得长方形的长是4cm，宽是3cm．长方形的实际面积是多少？
<gadget id="calculator">1 / 400</gadget>
<output>1/400 = around 0.0025</output>

<gadget id="calculator">4 / (1/400) / 100</gadget>
<output>16</output>

<gadget id="calculator">3 / (1/400) / 100</gadget>
<output>12</output>

<gadget id="calculator">16 * 12</gadget>
<output>192</output>

<result>192</result>