The meaning of this question is to randomly select 10 numbers from 0 to 9 to form two 3-digit numbers (numbers cannot be reused). The hundredth digit of the first number is 6 and the hundredth digit of the second number is 3, so their sum should be about 1000 (more than 600 plus more than 300), and their difference is about 300 (more than 600 minus more than 300).