Write the 10 numbers from 1 to 10 on 10 identical cards, put the cards upside down on the table, and touch any card. What is the probability of getting a prime number?
将1～10这10个数写在10张同样的卡片上，将卡片打乱反放在桌子上，任意摸一张卡片，摸到素数的可能性为多少．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

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