An instrument part is drawn on a 20:1 drawing, and its length is measured to be 6 cm. What is the actual length of this part in millimeters?
一个仪器零件画在一张20：1的图纸上，量得其长度为6厘米，这个零件实际长度是多少毫米．
<gadget id="calculator">20 / 1</gadget>
<output>20</output>

<gadget id="calculator">6 / 20</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * 10</gadget>
<output>3</output>

<result>3</result>