There are 3 white table tennis balls numbered 1, 2, and 3 in box A, and 3 yellow table tennis balls numbered 4, 5, and 6 in box B. Now take 1 ping-pong ball randomly from each box, what is the probability that the sum of the numbers of the ping-pong balls taken out is greater than 6?
甲盒子中有编号为1、2、3的3个白色乒乓球，乙盒子中有编号为4、5、6的3个黄色乒乓球．现分别从每个盒子中随机地取出1个乒乓球，则取出乒乓球的编号之和大于6的概率为多少．
<gadget id="calculator">3 + 6</gadget>
<output>9</output>

<gadget id="calculator">6 / 9</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>