Zhang Li was born in July 1992. If you want to guess which day her birthday is in July, what is the probability of guessing right once?
张力是1992年7月出生的，要猜她的生日是7月的哪一天，一次就猜对的可能性是多少．
<gadget id="calculator">1 / 31</gadget>
<output>1/31 = around 0.032258</output>

<result>1/31 = around 0.032258</result>