9. Can swapping any two digits of 1234567891011 result in a perfect square? Please explain your reasoning.
【Answer】No
【Analysis】
The sum of the digits of the original number is $1+2+3+\cdots+9+1+0+1+1=48$, which is a multiple of 3, and swapping the positions of the digits does not change the sum of the digits, so no matter how you adjust, the resulting number will definitely be a multiple of 3; and if a square number is a multiple of 3, it must also be a multiple of 9, but 48 is not a multiple of 9, so it is impossible to obtain a perfect square by swapping the positions of the digits.