Teacher Liu buys a bundle of pencils and distributes it to 6 people on average, leaving 1 pencil in the end; How many pencils does Mr. Liu buy at least?
刘老师买回一捆铅笔，把它平均分给6个人，最后余下1枝；如果把它平均分给4个人，最后也余下1枝．刘老师买回的铅笔最少有多少枝？
<gadget id="calculator">2 * 3 * 2</gadget>
<output>12</output>

<gadget id="calculator">12 + 1</gadget>
<output>13</output>

<result>13</result>