A three-digit number, write 1 in front of it, the resulting four-digit number is 9 times the original three-digit number. What is the original three-digit number?
一个三位数，在它的前面写上1，所得的四位数是原来的三位数的9倍．原来的三位数是多少？
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">1_000 / 8</gadget>
<output>125</output>

<result>125</result>