There are 9 balls in the pocket, marked with numbers from 1 to 9 respectively. A and B take turns touching a ball from their pockets, and put it back after touching it. One point is awarded for balls 1, 2, 3, and 4, one point for balls 6, 7, 8, and 9, and one point is deducted for balls 5. What is the probability that A and B will win?
口袋里有9个球，分别标有1～9个数字．甲乙两人轮流从口袋里摸一个球，摸完后再放回．摸到1、2、3、4号球甲得一分，摸到6、7、8、9号球乙得一分，摸到5号球都扣一分．甲乙获胜的可能性各是多少？
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(4/9) - (1/9)</gadget>
<output>1/3 = around 0.333333</output>

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