Expand the numerator of (2/13) by 4 times, to keep the size of the fraction constant, what should its denominator be.
把(2/13)的分子扩大4倍，要使分数的大小不变，它的分母应该变成多少．
<gadget id="calculator">13 * 4</gadget>
<output>52</output>

<result>52</result>