6. (12 points) In the vertical calculation shown in the figure, different Chinese characters represent different digits from “0-9”. If the vertical calculation is correct, then the smallest four-digit number represented by the characters 展示活动 is $\qquad$ .



Translating the text into English while preserving the original formatting and line breaks, the result is as follows:

6. (12 points) In the vertical calculation shown in the figure, different Chinese characters represent different digits from “0-9”. If the vertical calculation is correct, then the smallest four-digit number represented by the characters 展示活动 is $\qquad$ .
【Answer】Solution: To make the sum the smallest, the number must be 1, exhibition must be 2, study must be 9, demonstration must be 0, and the minimum value of the activity is 34,

After testing, $1956+78=2034$ holds true, so the smallest four-digit number represented by the demonstration activity is 2034, hence the answer is 2034.