A and B race up the stairs from the ground floor. When A reaches the third floor, B happens to be on the second floor. According to this calculation, A runs to the 15th floor, and B runs to the number of floors.
甲、乙两人从底楼开始比赛爬楼梯，甲跑到第3层时，乙恰好到第2层，照这样计算，甲跑到第15层，乙跑到第多少层．
<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">14 * (1/2)</gadget>
<output>7</output>

<gadget id="calculator">7 + 1</gadget>
<output>8</output>

<result>8</result>