在分数乘法中,我们可根据乘法交换律推出:几个分数相乘,交换它们的分子或分母的位置,积不变.例如,?(此规律请读者自证).应注意的是,式中若含带分数,必先化成假分数.根据这一新规律,结合运用其他运算定律(或性质),可特殊地将其运用在含分数乘法的四则运算中,使某些分数四则运算变得比较简便.例如, In fractional multiplication, we can derive from the law of multiplication commutation: multiplying several fractions and exchanging their numerator or denominator positions, for example,? (This rule invites the reader to prove himself.) It should be noted that equation According to this new law, combined with the use of other laws of operation (or properties), it can be specially used in the four operations with fractional multiplication, so that some fractional four arithmetic operation It's easier