66乘21加19乘21加85乘19用简便算法怎么算_数学解答

66乘21加19乘21加85乘19用简便算法怎么算

人气：487 ℃　时间：2019-09-22 10:07:00

解答

66x21+19x21+85x19
=(66+19)x21+85x19
=85x21+85x19
=85x(21+19)
=85x40
=(90-5)x40
=90x40-5x40
=3600-200
=3400