Among the four numbers 2, 3, 5 and 7, two of them can be selected to form some real fractions, and how many of them can be transformed into finite decimals account for the total number.
在2、3、5和7四个数中，任选两个可以组成一些真分数，其中能化成有限小数的占总数的多少．
<gadget id="calculator">2 / 6</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>