The original length of a pencil is 8 cm and 8 mm, and 9 mm is used. How long is the pencil now?
一支铅笔原长8厘米8毫米，用去9毫米，现在这支铅笔还有多长？
<gadget id="calculator">88 - 9</gadget>
<output>79</output>

<result>79</result>