Regulation: \overline{abcd}=1000a+100b+10c+d. It is known that \overline{4xyz}*2=\overline{xyz8}, the same letter represents the same number, and different letters represent different numbers. Then \overline{xyz}=how much.
规定：\overline{abcd}=1000a+100b+10c+d．已知\overline{4xyz}*2=\overline{xyz8}，相同字母表示相同的数字，不同的字母表示不同的数字．则\overline{xyz}=多少．
<gadget id="calculator">7_992 / 8</gadget>
<output>999</output>

<result>999</result>