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0.1+0.2+0.3+0.4+……+2.5的简便方法

类似高斯故事里的计算,让我们先观察一下算式,发现可以分组求和,首先为了方便计算可以先提取十分之一,然后再1+25 2+24 3+23 这样分成若干组和为26的算式,最后计算组数发现有12组,再加上落单的13,整理就得到最终结果32.5了,这是等差数列的...

0.1+0.3+0.5+0.7+……+0.99 =(0.1+0.3+...+0.9)+(0.11+0.13+...+0.99) =(0.1+0.9)*5/2+(0.11+0.99)*45/2 =2.5+22.5*1.1 =2.5+24.75 =27.25.

1.2×5.2一2.5÷0.3 =1.2x(5+0.2)-(2.4+0.1)÷0.3 =1.2x5+1.2x0.2-2.4÷0.3-0.1÷0.3 =0.3x4x5+0.24-8-1/3 =0.3x20+0.24-8-1/3 =6+0.24-8-1/3 =-2+0.24-1/3 ≈-2+0.24-0.34 =-2-0.1 =-2.1

(0.1*2*0.3*4*0.5*6*0.7*8*0.9*10*1.1)/(2.2*2.4*2.5*2.7) = 2*3*4*5*6*7*8*9*10*11/22*24*25*27*10*10 (约去2*5=10; 3*9=27,以及11,10) = 4*6*7*8/2*24*25 (约去6*8=2*24) =4*7/25 =28/25

1+1.1+2.5-3.2+0.4-1.3-0算一算,分一分。一共有几种分法 ...3"知道翻译:有好多种方法呢。 评论 | 0 0 分享 2016-04-11 18:10 shi...

1、0.4x(2.5-0.25)+2.9 =2.5*0.4-0.4*0.25+2.9 =1-0.1+2.9 =3.9-0.1 =3.8 2、1.25-1.25x0.8 =1.25*(1-0.8) =1.25*0.2 =0.25 3、11.25+11.25x0.8 =11.25*2-11.25*0.2 =22.5-2.25 =20.25 4、(0.25+2.5+25)x0.8 =(0.25+2.5+25)-(0.25+2.5+25...

=(1.2+0.8)*2.5 =2*2.5 =5

(1)1.97×0.25×0.4=1.97×(0.25×0.4)=1.97×0.1=0.197;(2)(2.5+0.25)×0.8=2.5×8+0.25×8=20+2=22;(3)3.2×12.5=(4×0.8)×12.5=4×(0.8×12.5)=4×10=40;(4)5.71×8.3-5.71×7.3=5.71×(8.3-7.3)=5.71×1=5.71;(5)0.25×0.44=0.25×(4×...

1.72+0.53+0.28+1.47 =(1.72+0.28)+(0.53+1.47) =2+2 =4 3.2×1.25×2.5 =4×0.8×1.25×2.5 =(4×2.5)×(0.8×1.25) =10×1 =10 3.9×99 =3.9×(100-1) =3.9×100-3.9×1 =390-3.9 =386.1

×÷7.2+0.2=0.3 解:×÷7.2=0.3-0.2 ×÷7.2=0.1 ×=0.1×7.2 x=0.72 ×÷7.2-0.2=0.3 解:×÷7.2=0.3+0.2 ×÷7.2=0.5 ×=0.5×7.2 x=3.6

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