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1、整数加法运算定律推广到小数1. 填空(1) 3.45+2.34+15.66=3.45+(2.34+15.66),这是运用了( )(2) 2.83+2.68+1.17=2.83+117+2.68,这是运用了( )(3) (4.2+12.5)+7.5=+(+)(4) 28.46-7.4-2.6=28.46-(7.42.6)2.下面各题怎样简便就怎样算。61.4+6.32+3.6832.68-2.47-2.537.63-4.76+2.3713.7+0.98+1.02+6.315.24+(7.59+4.76)60.21-(10.21-4.77)3.买这四样物品要多少钱?附答案:1.加法结合律 加法交换
2、律 4.2+(12.5+7.5) “+”2.61.4+6.32+3.6832.68-2.47-2.537.63-4.76+2.37=61.4+(6.32+3.68)=32.68-(2.47+2.53) =7.63+2.37-4.76=61.4+10 =32.68-5 =10-4.76=71.4 =27.68 =5.2413.7+0.98+1.02+6.315.24+(7.59+4.76)60.21-(10.21-4.77)=(13.7+6.3)+(0.98+1.02) =15.24+4.76+7.59 =60.21-10.21+4.77=20+2 =20+7.59 =50+4.77=22 =27.59 =54.773.38.60+72.50+21.40+87.50=(38.60+21.40)+(72.50+87.50)=60+160=220元