999×8 111×28的简便方法计算

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999×8+1111×28简便计算=111x9x8+(1110+1)x28=111x72+1110x28+1x28=111x72+111x10x28+28=111x(72+280)+28=111x352+28=111x(300+52)+28=111x300+111x52+28=33300+(5772+28)=33300+5800=39100

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　　999x8=(1000-1)x8=8000-8=7992; 111x28=(100+10+1)x28=2800+280+28=3108

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999x8+111x28
=111x（9x8+28）
=111x100
=11100

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