【Question 12】Given three natural numbers $1,2,3$, perform an operation on these three numbers, replacing one of the numbers with the sum of the other two, and perform this operation 9 times. After these operations, the maximum possible value of the largest number among the three natural numbers obtained is $\qquad$ _.
Analysis: To maximize the largest number among the three natural numbers after multiple operations, we only need to replace the smallest number among the three with the sum of the other two each time.
Original data: $1,2,3$
After 1 operation: 5, 2, 3
After 2 operations: 5, 8, 3
After 3 operations: 5, 8, 13
After 4 operations: $21,8,13$
After 5 operations: $21,34,13$
After 6 operations: $21,34,55$
After 7 operations: 89, 34, 55
After 8 operations: 89, 144, 55
After 9 operations: 89,144, 233
So the maximum possible value of the largest number is 233