Each paper clip is 30 mm long and 1 mm thick, so how many mm are the three paper clips buckled together?
每个回形针长30毫米，粗1毫米，这样三个回形针针扣起来长多少毫米．
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">1 * 4</gadget>
<output>4</output>

<gadget id="calculator">90 - 4</gadget>
<output>86</output>

<result>86</result>