Use the numbers 0, 1, 2, 3, 4, 5 to form six digits with different numbers, and arrange them in ascending order, what is the 502nd number?
用数码0，1，2，3，4，5组成各位数码都不相同的六位数，并按从小到大的顺序排列，第502个数是多少．
<result>504_231</result>