A four-digit number, the first number on the left is 7, if this number is adjusted to the last digit, the number will be reduced by 864, find the four-digit number (solution of the column equation)
一个四位数，左边的第一个数字是7，如果把这个数字调到最后一位，则这个数要减少864，求出这个四位数(列方程解答)
<gadget id="calculator">7_000 - 864 - 7</gadget>
<output>6_129</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">6_129 / 9</gadget>
<output>681</output>

<gadget id="calculator">7_000 + 681</gadget>
<output>7_681</output>

<result>7_681</result>