Every time I take half of the cups in the box, I put one back in. After taking a total of 487 times, there are still 2 cups in the box. How many cups are there in the box?
每次拿箱子的杯子的一半又放回去一个，一共拿了487次后，箱子里还有2个杯子，箱子里原来有多少个杯子．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

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

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

<result>2</result>