There is a column of numbers: (1/1), (1/2), (2/2), (1/3), (2/3), (3/3), (1/4), (2/4 ), (3/4), (4/4), ... then (9/10) is the number among them.
有一列数：(1/1)，(1/2)，(2/2)，(1/3)，(2/3)，(3/3)，(1/4)，(2/4)，(3/4)，(4/4)，…那么(9/10)是其中第多少个数．
<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<gadget id="calculator">45 - 1</gadget>
<output>44</output>

<result>44</result>