Use the four numbers 1, 3, 5, and 7 to form a fraction that is closest to pi. What is the fraction?
用1、3、5、7这四个数字，组成一个最接近圆周率的分数，这个分数是多少．
<gadget id="calculator">53 / 17</gadget>
<output>53/17 = around 3.117647</output>

<result>53/17 = around 3.117647</result>