Pens are 9 yuan each. Bought 2 boxes of pens, 4 pens in each box. How much did you spend in total?
钢笔每只9元．买了2盒钢笔，每盒4支．共花去多少钱？
<gadget id="calculator">2 * 4 * 9</gadget>
<output>72</output>

<result>72</result>