8. (3 points) In the multiplication equation GrassGreen・FlowerRed $=$ SpringBright, the Chinese characters represent non-zero digits, and different characters represent different digits. Therefore, the smallest four-digit number represented by SpringBright is $\qquad$

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【Analysis】According to the problem, we can deduce the solution by using the method of integer multiplication.
【Solution】There are 9 Chinese characters, and there is no 0, so the 9 characters correspond to the 9 digits from 1 to 9;
To get the smallest result, "flower" and "grass" can only be 1 and 2; According to the principle that the product is maximized when the difference between two numbers with a fixed sum is minimized, we choose "flower" to be 1 and "grass" to be 2; "spring" can only be 3 or 4;

In "grass green, flower red, spring bright and sunny," the three digits in the units place must include at least two of the digits 5, 6, 7, 8, 9;
Multiplying a number by 5 results in a product ending in 0 or 5, so 5 cannot be used;
Since $6 \times 7 = 42$, the units digit is 2, which would cause a repetition and is not allowed;
By elimination, the only possibilities are $6 \times 9 = 54$, $7 \times 8 = 56$, or $7 \times 9 = 63$;
When $7 \times 8 = 56$, we have $28 \times 157 = 4396$, which is the smallest result.
Therefore, the answer is: 4396.