There are ten cards with the same number on the back, 1 to 10, put them on the table in random order (back side up), and then randomly draw one of them. The possibility that the number on the drawn card is a prime number is How many
有1～10这十张背面完全一样的数字卡片，把它们打乱顺序放在桌面上(背面朝上)，然后从中任意摸出一张，摸到的卡片上的数字是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>