99+9+999怎么用乘法结合律
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/08/19 17:14:38
99+9+999怎么用乘法结合律
![99+9+999怎么用乘法结合律](/uploads/image/z/19668359-47-9.jpg?t=99%2B9%2B999%E6%80%8E%E4%B9%88%E7%94%A8%E4%B9%98%E6%B3%95%E7%BB%93%E5%90%88%E5%BE%8B)
99+9+999
=(10-1)+(100-1)+(1000-1)
=1000+100+10-1×3
=1110-3
=1107
或者99+9+999
=9×1+9×11+9×111
=9×(111+11+1)
=9×123
=1107
=(10-1)+(100-1)+(1000-1)
=1000+100+10-1×3
=1110-3
=1107
或者99+9+999
=9×1+9×11+9×111
=9×(111+11+1)
=9×123
=1107