Master Yang originally processed 240 parts in 5 hours. After technological innovation, these parts only need 4 hours. By what percentage is the time shortened?
杨师傅原来5小时加工零件240个．技术革新后，这些零件只需要4小时．时间缩短了百分之几？
<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>