There are 2 yellow ping pong balls and 8 white ping pong balls in a box. If you touch a ball at random, the probability of getting a yellow ball is (1/3), how many yellow balls need to be added to the box.
一个盒子里有2个黄乒乓球，8个白乒乓球，任意摸一个球，要想摸到黄球的可能性是(1/3)，需要往盒子里加多少个黄球．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">8 / (2/3)</gadget>
<output>12</output>

<gadget id="calculator">2 + 8</gadget>
<output>10</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<result>2</result>