Some pens are 8 yuan each, and now they are promoting "buy four get one free". If the teacher wants to buy one for each of the 40 students in the class, what is the minimum cost?
某种钢笔每支8元，现在还推销"买四送一"．老师要为全班40人每人买一支，最少要花多少元？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<gadget id="calculator">40 - 8</gadget>
<output>32</output>

<gadget id="calculator">8 * 32</gadget>
<output>256</output>

<result>256</result>