Use the nine numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9 to form three three-digit numbers (each number is used only once), what is the maximum sum of these three three-digit numbers?
用1、2、3、4、5、6、7、8、9这九个数字组成三个三位数(每个数字只用一次)，这3个三位数之和最大是多少．
<gadget id="calculator">9 * 100</gadget>
<output>900</output>

<gadget id="calculator">8 * 100</gadget>
<output>800</output>

<gadget id="calculator">7 * 100</gadget>
<output>700</output>

<gadget id="calculator">6 * 10</gadget>
<output>60</output>

<gadget id="calculator">5 * 10</gadget>
<output>50</output>

<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">900 + 800 + 700 + 60 + 50 + 40 + 1 + 2 + 3</gadget>
<output>2_556</output>

<result>2_556</result>