84*17-42*2+21*136的简便运算

84*17-42*2+21*136的简便运算
84*17-42*2+21*136的简便运算

84*17-42*2+21*136的简便运算
84*17-42*2+21*136=4*21*17-21*2*2+21*136=21*68-21*4+21*136=(68-4+136)*21=200*21=4200

84*17-42*2+21*136
=84*17-84+21*4*34
=84*17-84+84*34
=84*(17-1+34)
=84*50
=4200

=42*2*17-42*2+21*2*68
=42*34-42*2+42*68
=42*(34-2+68)
=42*100
=4200