After the decimal point of a number is moved one place to the left, the number will decrease by 4.05. What is the original number?
一个数的小数点向左移动一位后，这个数就减少4.05，这个数原来是多少．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">4.05 / 9</gadget>
<output>0.45</output>

<gadget id="calculator">0.45 * 10</gadget>
<output>4.5</output>

<result>4.5</result>