Put 8 red balls and 5 blue balls into a pocket, draw one randomly from the pocket, what is the probability of drawing a blue ball?
把8个红球和5个蓝球放进一个口袋里，从口袋里任意摸出一个，摸出蓝球的可能性是多少．
<gadget id="calculator">5 + 8</gadget>
<output>13</output>

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

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