A pen is priced at 12 yuan each, and a "buy 4 get 1 free" event is held to welcome the "11th". How much is each pen cheaper than the original price now?
一种钢笔每枝售价12元，迎"十一"举行"买4送1"活动，现在每枝比原价便宜多少钱？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">12 * (4/5)</gadget>
<output>48/5 = around 9.6</output>

<gadget id="calculator">12 - (48/5)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>