756x999756x999简算急

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756x999756x999简算急

756x999756x999简算急
756x999756x999简算

756x999756x999简算急
756x999=756*(1000-1)=756000-756=755244

756×999756×999
=756×(999000+756)×999
=756×(999000+756)×(1000-1)
=(756000-756)×(999000+756)
=(877500-121500-756)(877500+121500+756)
=[877500-(121500+756)][877500+(121500+756)]
=(877500-122256)(877500+122256)
=877500^2-122256^2
=755059720464

756×999756×999
=756×(999000+756)×999
=756×(999000+756)×(1000-1)
=(756000-756)×(999000+756)
=(877500-121500-756)(877500+121500+756)
=[877500-(121500+756)][877500+(121500+756)]
=(877500-122256)(877500+122256)
=877500^2-122256^2
=755059720464
好烦琐啊.