If one number is removed from positive integers 1 to N, the average value of the remaining N-1 numbers is 16.3; what is the removed number?
从正整数1～N中去掉一个数，剩下的N-1个数的平均值是16.3；去掉的数是多少．
<gadget id="calculator">1 + 31</gadget>
<output>32</output>

<gadget id="calculator">31 / 2</gadget>
<output>31/2 = around 15.5</output>

<gadget id="calculator">32 * (31/2)</gadget>
<output>496</output>

<gadget id="calculator">31 - 1</gadget>
<output>30</output>

<gadget id="calculator">30 * 16.3</gadget>
<output>489</output>

<gadget id="calculator">496 - 489</gadget>
<output>7</output>

<result>7</result>