小学生应该熟悉的常用数值，真是好资料，这个应该转！

一、 常用分数、小数的互化

1/2 =0.5=50 %

1/3 ≈0.333 =33.3%

2/3 ≈0.667=66.7%

1/4 =0.25=25 %

3/4 =0.75=75 %

1/5 =0.2=20 %

2/5 =0.4=40 %

3/5 =0.6=60 %

4/5 =0.8=80 %

1/6 ≈0.167=16.7%

5/6 ≈ 0.833=83.3%

1/8 =0.125=12.5 %

3/8 =0.375=37.5 %

5/8 =0.625=62.5%

7/8 =0.875=87.5 %

1/9 ≈ 0.111=11.1%

1/10 =0.1=10%

1/20=0.05=5%

3/20=0.15=15%

7/20=0.35=35%

9/20=0.45=45%

11/20=0.55=55%

13/20=0.65 =65%

17/20=0.85=85%

19/20=0.95=95%

1/16 =0.0625=6.25%

1/32 =0.03125=3.125%

1/64 =0.015625=1.5625%

1/7 =0. 142857 142857 … ≈0.143 =14.3%

2/7 =0. 285714 285714 … ≈0.286=28.6%

3/7 =0. 428571 428571 … ≈0.429=42.9%

4/7 =0. 571428 57142 … ≈0.571=57.1%

5/7 =0. 714285 714285 … ≈0.714=71.4%

6/7 =0. 857142 857142 … ≈0.857=85.7%

熟记：142857

二、 常用圆周率的计算

3.14 ×1=3.14

3.14 ×2=6.28

3.14 ×3=9.42

3.14 ×4=12.56

3.14 ×5=15.70

3.14 ×6=18.84

3.14 ×7=21.98

3.14 ×8=25.12

3.14 ×9=28.26

3.14 ×10=31.40

3.14 ×11=34.54

3.14 ×12=37.68

3.14 ×16=50.24

3.14 ×18=56.52

3.14 ×20=62.80

3.14 ×25=78.50

3.14 ×32=100.48

3.14 ×36=113.04

3.14 ×49=153.86

3.14 ×64=200.96

3.14 ×81=254.34

3.14 ×121=379.94

三、常用的完全平方数

1 ² =1

2 ² =4

3 ² =9

4 ² =16

5 ² =25

6 ² =36

7 ² =49

8 ² =64

9 ² =81

10 ² =100

11 ² =121

12 ² =144

13 ² =169

14 ² =196

15 ² =225

16 ² =256

17 ² =289

18 ² =324

19 ² =361

20 ² =400

四、常用的立方数

1 ³ =1

2 ³ =8

3 ³ =27

4 ³ =64

5 ³ =125

6 ³ =216

7 ³ =343