【Question 25】  
Among the positive integers whose digit sum is 50 and are multiples of 11, the second smallest number is $\qquad$.
【Analysis and Solution】
Number problem.
If the number is small, the number of digits should be less, and the maximum for each digit is 9.
First, consider the sum of digits being $50, 50 \div 9 = 5 \cdots \cdots .5$, so it must be at least a six-digit number.
When the first digit is 5, it can only be 599999, which is not a multiple of 11;
When the first digit is 6, from smallest to largest, they are $689999, 698999, 699899, 699989, 699998$, none of which are multiples of 11;
When the first digit is 7, from smallest to largest, they are $779999, 788999, 789899, \ldots . .$. Among them, 779999 and 789899 are multiples of 11. In summary, the second smallest number with a digit sum of 50 and a multiple of 11 is 789899.