12. (10 points) Fill in each cell with a number from $1 \sim 6$, such that the numbers in each row and each column are unique. The numbers on the right indicate the sum of the three-digit number, the two-digit number, and the single-digit number formed by the first three numbers, the middle two numbers, and the last number, respectively, separated by thick lines. What is the five-digit number $\overline{\mathrm{ABCDE}}=$ $\qquad$
【Answer】Solution: Based on the unit digit and the unit digit that can form the result: If the unit digit of the result is 5, then the unit digits of these 3 numbers must be the combination of $4,5,6$.

Unique method, elimination method: Only one number can be filled in.
First digit analysis method: The result of the sixth row is 669, so the hundred's digit must be 6.
As shown in the figure:
Therefore, the answer is: 41244