The fifth and sixth grades in Xiji County held a "Gizmo" competition. The sixth grade students submitted 320 works, and the fifth grade submitted 20% less than the sixth grade. How many works did the fifth grade hand in?
西吉县五、六年级举行"小发明"比赛，六年级学生上交320件作品，五年级比六年级少交20%．五年级交了多少件作品？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">320 * (4/5)</gadget>
<output>256</output>

<result>256</result>