from decimal import Decimal a1 = 0.00000999 a2 = 13400 b1 = a1*a2 print(b1) # 0.13386599999999999 a1=Decimal(0.00000999) a2=Decimal(13400) b1 = a1*a2 print(b1) #0.1338659999999999895440921591 a1=Decimal(str(0.00000999)) a2=Decimal(str(13400)) b1 = a1*a2 print(b1) #0.13386600 正确 #注意用Decimal函数,需要用str()函数转成字符型