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125×235-26×235+235 238×99 2+4+6+8···+80 2000-3-6-9···-51-54

来源:学生作业帮 编辑:大师作文网作业帮 分类:数学作业 时间:2024/11/17 09:13:10
125×235-26×235+235 238×99 2+4+6+8···+80 2000-3-6-9···-51-54 它们的简便计算!
125×235-26×235+235 238×99 2+4+6+8···+80 2000-3-6-9···-51-54
125×235-26×235+235
=235×(125-26+1)运用了乘法分配律
=235× 100
=23500
238×99
=238×(100-1)
=238×100-238
=23800-238
=23562
2+4+6+8···+80
=(2+80)×40÷2
=82×20
=1640
2000-3-6-9···-51-54
=2000-(3+6+9…+51+54)
=2000-(3+54)×18÷2
=2000-57×9
=2000-513
=1487