49*25+21*31的简便计算

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49*25+21*31的简便计算
49*25+21*31的简便计算

49*25+21*31的简便计算
=50*25-25 + 21*30+21
=(1250+630+20)+1-25
=1900-24
=1876

49*25+21*31
=7*7*25+7*3*31
=7(7*25+3*31)
=7(175+93)
=7*268
=7(270-2)
=7*270-14
=1890-14
=1876

49*25+21*31=49*25+21*25+21*6=(49+21)*25+21*6=70*25+21*6=1750+126=1876

49*25+21*31
=50*25-25+(20+1)(30+1)
=1250-25+600+20+30+1
=1250+650-24
=1900-24
=1876