Put ten cards with 1 to 10 written on them in a bag, close your eyes and take out one at random. What is the probability of getting a prime number?
把分别写有1到10的十张卡片放入袋中，闭上眼睛任意摸出一张，摸到质数的可能性是多少．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>