For a fraction, the numerator is expanded to 2 times the original, the denominator is reduced to the original (1/2), how many times the current fraction is expanded to the original
一个分数，将分子扩大为原来的2倍，分母缩小为原来的(1/2)，现在的分数扩大为原来的多少倍
<result>4</result>