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0.2,0.3,0.5,0.8,1.3,2.1()怎么巧算

0.3-0.2=0.1 0.5-0.3=0.2 0.8-0.5=0.3 1.3-0.8=0.5 2.1-1.3=0.8 ()-2.1=1.3 ()=3.4

10-0.1-0.2-0.3-0.4-0.5-0.6-0.7-0.8-0.9=5.5

第一步:计算1×2×3×4×5×6×7×8×9=362880 第二步:查看共有几位小数:9位 第三部:从右往左数九位,不足的位用0代替,确定小数点位置,结果:0.000362880

0.1*0.2*0.3*0.4*0.5*0.6*0.7*0.8*0.9怎样巧算

(1)1.2×0.4+1.3×0.4,=(1.2+1.3)×0.4,=2.5×0.4,=1;(2)(1.25+0.36)×0.2,=1.25×0.2+0.36×0.2,=0.25+0.072,=0.322;(3)7.2×0.3+28×0.03,=72×0.03+28×0.03,=(72+28)×0.03,=100×0.03,=3;(4)0.25×0.56×0.4,=0.25×0.4×0.56...

1、3.125×0.4×0.8×0.25 =(3.125×0.8)×(0.4×0.25) =2.5×0.1 =0.25 2、(0.8×1.2+0.8×0.05)×3.4 =0.8×(1.2+0.05)×3.4 =0.8×1.25×3.4 =1×3.4 =3.4 3、72÷2.5 =(72×4)÷(2.5×4) =288÷10 =28.8 4、111.1÷1.11×3.33 =111.1×(3.33÷1.11) =...

(1.25+0.5+2.5)×6.4 =1.25×6.4+0.5×6.4+2.5×6.4 =1.25×0.8×8+0.5×2×3.2+2.5×0.4×16 =1×8+1×3.2+1×16 =8+3.2+16 =27.2

此类题要分析找出数字之间的规律,凑整数是最简单的方法,1+9=10 、2+8=10 、 3+7=10、4+6=10、 10+5=15 四个10一个15相加=55不用笔算心算几秒就能得出答案 有网友用两头向中间相加得出的规律为每两个数字是11,共五个11最后结果=55也很巧妙。学...

0.25*0.4*1.25+1.25*8*0.4

10+9.9-9.8+9.7+……+0.3-0.2+0.1 = 10+(9.9-9.8)+(9.7-9.6)+……+(0.3-0.2)+0.1 = 10+ 50*0.1 = 15

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