66乘21加19乘21加85乘19用简便算法怎么算

分类: 作业答案 • 2021-12-18 22:42:05

问题描述：

答

66乘21加19乘21加85乘19
=21*(66+19)+85*19
=85*(21+19)
=85*40
=3400

答

66×21+19×21+85×19
=(66+19)×21+85×19
=85×21+85×19
=85×(21+19)
=85×40
=3400

答

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