Xiao Ming participates in a lottery. There are 8 red balls and 5 yellow balls in total. One is drawn each time. What is the probability of getting a red ball for the first time?
小明参加抽奖活动，一共有8个红球，5个黄球，每次抽一个，第一次抽到红球的可能性为多少．
<gadget id="calculator">8 + 5</gadget>
<output>13</output>

<gadget id="calculator">8 / 13</gadget>
<output>8/13 = around 0.615385</output>

<result>8/13 = around 0.615385</result>