40%乘以0.003%等于0.000012
也就是0.4乘以0.003%，先不管那个“%”，先算0.4×0.003=0.0012，最后再把“%”加上，结果为0.0012%
就是0.4×0.00003=0.000012
0.000012
万分之0.012
