Use the 9 numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9 each once to form a correct subtraction formula in which the minuend, subtrahend, and difference are all three-digit numbers, then in this formula What is the largest difference?
用1、2、3、4、5、6、7、8、9这9个数字各一次，组成一个被减数、减数、差都是三位数的正确的减法算式，那么这个算式中的差最大是多少？
<gadget id="calculator">936 - 152</gadget>
<output>784</output>

<result>784</result>