For a simplest fraction, its numerator is enlarged by 2 times, and the denominator is reduced to the original (1/2). This simplest fraction is how much the original simple fraction is.
一个最简分数，把它的分子扩大2倍，分母缩小为原来的(1/2)，这个最简分数是原来简分数的多少．
<result>4</result>