If you touch any one in a box containing 3 red balls and 6 white balls, what is the probability of getting a red ball?
在装了3个红球、6个白球的盒子里任意摸一个，摸到红球的可能性是多少．
<gadget id="calculator">3 + 6</gadget>
<output>9</output>

<gadget id="calculator">3 / 9</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>