简便算法是:3.24×0.4×0.25=3.24×0.1=0.324
先算0.4×0.25等于0.1，再算3.24×0.1等于0.324。
先算后面两个数相乘
3.24*0.4*0.25=3.24*（0.4*0.25）=3.24*0.1=0.324
