When Xiao Ming was doing an addition, he mistakenly left out the single digit zero of an addend, and the result was 405 less than the correct result. What is this addend.
小明在做一道加法时，错把一个加数的个位零给漏掉了，结果比正确结果少了405．这个加数是多少．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">405 / 9</gadget>
<output>45</output>

<gadget id="calculator">45 * 10</gadget>
<output>450</output>

<result>450</result>