Add three numbers after 640 to form a six-digit number so that it can be divided by 3, 4, and 5 respectively. What is the smallest of such six-digit numbers?
在640后面补上三个数字，组成一个六位数，使它分别能被3、4、5整除，这样的六位数中最小的是多少．
<result>640_020</result>