Pick any two of the four cards marked 1, 2, 3, and 4, and what is the probability that the sum is an even number?
从标有1、2、3、4的四张卡片中任取两张，和是偶数的可能性是多少．
<gadget id="calculator">2 + 1 + 1 + 2</gadget>
<output>6</output>

<gadget id="calculator">2 / 6</gadget>
<output>1/3 = around 0.333333</output>

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