28+31+30+32+29+28+31简便计算

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28+31+30+32+29+28+31简便计算28+31+30+32+29+28+31简便计算28+31+30+32+29+28+31简便计算28+31+30+32+29+28+31=(28+32)

28+31+30+32+29+28+31简便计算
28+31+30+32+29+28+31
简便计算

28+31+30+32+29+28+31简便计算
28+31+30+32+29+28+31
=(28+32)+(31+29)+30+28+31
=60+60+60+29
=180+29
=209

(31+29)+(28+32)+(31+31+28)+30=240

28+31+30+32+29+28+31
=(28+32)+(29+31)+30+30+1+30-2=209

28+31+30+32+29+28+31
=(28+32)+(29+31)+(28+32)+30-1
=30*2+30*2+30*2+30-1
=30*7-1
=209

(28+32)+(31+29)+30+28+31
=60+60+30+59
=209

30*7-2+1+2-1-2+1
=210-1
=209