The scale on a part drawing is 6:1, if the length of the line segment measured on the drawing is 42 mm, what is the actual length?
一张零件图上的比例尺是6：1，如果在图上量得线段长是42毫米，实际长是多少．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">4.2 / (1/6)</gadget>
<output>25.2</output>

<result>25.2</result>