There are 640 old pipes used in the reconstruction of underground water pipes in a residential area in Shanghai. Now, the original 5-meter-long old pipes are replaced with new 8-meter-long pipes. How many new pipes are needed in total?
上海某小区改造地下自来水管道，旧管共用了640根铺成，现在用8米长的新管更换原来5米长的旧管，一共需要多少根新管？
<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">640 * (5/8)</gadget>
<output>400</output>

<result>400</result>