Fill in the eight numbers 1, 2, 3, 4, 5, 6, 7, and 8 into the eight "□" in the following formula (each number can only be used once), so that the number is the smallest, and the smallest number is How many. □□. □□-□□. □□
将1，2，3，4，5，6，7，8这八个数字填入下面算式的八个"□"内(每个数字只能用一次)，使得数最小，其最小得数是多少．□□．□□-□□．□□
<gadget id="calculator">51.23 - 48.76</gadget>
<output>2.47</output>

<result>2.47</result>