What is the probability of drawing a prime number from the 20 natural numbers 1 to 20?
从1～20这20个自然数中，抽到素数的可能性是多少
<gadget id="calculator">8 / 20</gadget>
<output>2/5 = around 0.4</output>

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