A pencil is originally 5 cm long, but 7 mm are used up, how many mm are left?
一枝铅笔原来长5厘米，用去了7毫米，还剩多少毫米？
<gadget id="calculator">5 * 10</gadget>
<output>50</output>

<gadget id="calculator">50 - 7</gadget>
<output>43</output>

<result>43</result>