五上小数简便计算专题(人教版)

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例1、5.76+13.67+4.24+6.33 =(5.76+4.24)+(13.67+6.33) =10+10

=20 例2、37.24+23.79-17.24 =37.24-17.24+23.79

=20+23.79

=43.79

二、运用乘法结合律进行简算:这种题型往往含特殊数字之间相乘(a×b)×c=a×(b×c)

特殊数字之间相乘:25×4=100 125×8=1000 遇到25或者125要看看另外一个因数能不能拆出4或者8来

例3、

4×3.78×0.25 =4×0.25×3.78 =1×3.78

=3.78 例4、

125×246×0.8 =125×0.8×246 =100×246

=24600

三、利用乘法分配律进行简算: (a+b)×c=a×c+b×c (a-b)×c=a×c-b×c

做这种题,一定不要急着去算,先要分析各数字之间的特殊关系。也就是先要仔细观察,找到做题的窍门。

例5、

(2.5+12.5)×40

=2.5×40+12.5×40 =100+500

=600 例6、

3.68×

4.79+6.32×4.79 =(3.68+6.32)×4.79

=10×4.79

=47.9

四、将比整十整百整千稍微大一点或者稍微小一点的数拆分后再利用乘法分配律进行简算:

例7、

34×9.9

=34×(10-0.1)

=34×10-34×0.1 =340-3.4

=336.6 例8、

57×101

=57×(100+1)

=57×100+57×1 =5757

五、连减与连除a-b-c=a-(b+c) a÷b÷c=a÷(b×c) 例15、56.5-3.7-6.3

=56.5-(3.7+6.3)

=56.5-10

=46.5

例16、32.6÷0.4÷2.5

=32.6÷(0.4×2.5)

=32.6÷1

=32.6

1.25×

2.5×32 0.25×16.2×4 4.36×12.5×8 25×32 125×0.72

26.86×25.66-16.86×25.66 5.7×99+5.7 (1.25-0.125)×8 15.6×13.1-15.6×3.1 3.9×2.7+3.9×7.3 27.5×3.7-7.5×3.7 7.09×10.8-0.8×7.09 18.76×9.9+18.76×0.1 3.65×10.1 0.89×100.1 0.65×101 8.9×1.01 0.79×199 7.8×1.1

100÷0.25÷8 6÷0.4÷0.25 300÷2.5÷0.4 17.8÷(1.78×4) 8.1÷4.5

4.56×0.4×2.5 12.5×2.7×0.8 12.5×32×0.25

2.5×32 12.5×56 25×0.36 0.25×10.4

12.5×8.8 99×0.35 3.7×1.8-2.7×1.8 48×0.56+44×0.48

95.7×0.28+6.3×0.28-0.28×2 1.08×9+1.08 9.8×7.7+2.3×7.7

0.125×96 0.25×3.2×8 3.2×02.5×1.25 12.5×10.8

(20-4)×0.25 1.83×1.7-0.7×1.83 0.37×199+0.37 5.28×99

45×1.58+5.5×15.8 0.279×343+0.657×279 9.16×1.53-0.053×91.6 4.5×21-55×2.1 6.23×10.1 4.2×6.51+3.49×4.2 0.89×99 314×0.043+3.14×7.2-31.4×0.1

2.5×7.1×4 16.12×99+16.12 5.2×0.9+0.9 4.3×50×0.2

0.75×199 0.86×15.7-0.86×14.7 0.25×36 4.2÷3.5

7.28×99+7.28 26×15.7+15.7×24 1.2×(9.6÷2.4)÷4.8 4.8-4.8×0.5

8.05×3.4+7.6 (3.275+0.625)×3.32×25 32+4.9-0.9 (1.25-0.125)×8

4.8×100.1 7.09×10.8-0.8×7.09 12.5×0.4×2.5×8 0.279×343+0.657×279

0.96 ÷(4.2 -3.4)× 1.25 9.5×99.8 4.8 ×(15 ÷ 2.4)8.7 × 17.4 - 8.7 × 7.4

2.5×(

3.8×0.04) 3.8×299.9 2.5×1.25×0.32 0.125×72

0.25×39+0.25 6.8×0.75÷0.25 48×0.56+44×0.48 12.5×56

13.5×0.98 12.5×8.8 95.7×0.28+6.3×0.28-0.28×2 9.5×99

9.16×1.53-0.053×91.6 3.9÷(1.3×5) 4.2÷3.5 40.5 ÷ 0.81 × 0.18

15÷(0.15×0.4) 63.4÷2.5÷0.4 3.6-3.6×0.75 (4.23+6.17)×0.8

4.4×0.8-3.4×0.8 (9.37+9.37+9.37+9.37)× 2.5

5.93+0.19+2.81 1.76+0.195+3.24 4.8+8.63+5.2+0.37 2.35+1.713+0.287+7.65 1.57+0.245+7.43

6.02+3.6+1.98

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