7. (3 points) $11 \times 11=121, \quad 111 \times 111=12321, \quad 1111 \times 1111=1234321,1111111 \times 1111111$ $=$ . $\qquad$
【Answer】Solution: According to the analysis, we have:
$$
111111 \times 1111111=1234567654321,
$$

Therefore, the answer is: 1234567654321.