Stationery store promotion, each pencil is 0.5 yuan, if you buy 3 pencils at a time, you will get 1 pencil. Xiao Ming needs 12 pencils, and he will have to pay at least RMB to buy them in this store.
文具店促销，每支铅笔0.5元，如果一次购买3支就赠送1支．小明需要12支铅笔，他到这个店买，至少要付多少元．
<gadget id="calculator">0.5 * 9</gadget>
<output>4.5</output>

<result>4.5</result>