A pencil is originally 8 cm 7 mm long, but 9 mm is used up. How long is this pencil now?
一枝铅笔原来长8厘米7毫米，用去了9毫米．现在这枝铅笔有多长？
<gadget id="calculator">87 - 9</gadget>
<output>78</output>

<gadget id="calculator">78 / 10</gadget>
<output>39/5 = around 7.8</output>

<result>39/5 = around 7.8</result>