Each pencil in the stationery store is 0.8 yuan, and now there is a promotion, if you buy 3 pencils at one time, you will get 1 free. Wang Li needs 12 pencils, what is the minimum amount he will pay now.
文具店每支铅笔是0.8元，现在进行促销，如果一次性购买3支就赠送1支．王立需要12支铅笔，他现在至少要付多少元．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">0.8 * 9</gadget>
<output>7.2</output>

<result>7.2</result>