1. Move the decimal point

2. 37.2 0.372 3.72 372 Observe the numbers above，
Observe the numbers above，
what’s the same,what’s the different？
Can you put in order of size from biggest to smallest?

3. What does each number mean in its place?
25.763
1.023
0.505

4. 372
37.2
3.72
0.372
What is the relationship among them?

5. 10×0.001=0.01

6. 10×0.01=0.1

7. 0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1
10×0.1=1

8. Observe the position of the decimal point in three multiplication equation, what can you find?
0.001×10=0.01
0.01×10=0.1
0.1×10=1
When you multiply by 10, you move the decimal point one place to the right .

9. When we know the multiplication fact ,can you find the related division facts?
0.001×10=0.01
0.01×10=0.1
0.1×10=1
0.01÷10=0.001
0.1÷10=0.01
1÷10=0.1
Observe the position of the decimal point in three division equations, what can you find?

10. Observe the position of the decimal point in three division equations, what can you find?
0.01÷10=0.001
0.1÷10=0.01
1÷10=0.1
When you divide by 10, you move the decimal point one place to the left . .

11. Have a try 14.1 Omit the decimal point 141 Add a zero 1410 1.41×10=
1.41×100=
1.41×1000=
14.1
move the decimal point one place to the right
move the decimal point two places to the right
move the decimal point three places to the right
Omit the decimal point
141
Add a zero
1410

12. Exercise
93.07×10=
93.07×100=
93.07×1000=
93.07×10000=
930.7
9307
93070
930700

13. If there is no digit in front of the decimal point,add 0.
Division facts
1.41 ÷10 =
1.41 ÷100=
1.41÷1000=
0.141
move the decimal point one place to the left
move the decimal point two places to the left
move the decimal point three places to the left
0.0141
If there is no digit in front of the decimal point,add 0.

14. Exercise
93.07÷10=
93.07÷100=
93.07÷1000=
93.07÷10000=
9. 307
0.9307

15. Do the following calculations
4.23×10
0.63×10
0.427×100
1000×0.64
141.2÷100
19.3÷10
47÷100
16÷1000
=42.3
=1.412
=6.3
=1.93
=42.7
=0.47
=640
=0.016

16. Copy and complete 0.45×（ ）=4.5 43÷（ ）=0.43 10 100 0.45×（ ）=45
0.45×（ ）=4.5
0.45×（ ）=45
0.45×（ ）=4500
43÷（ ）=0.43
43÷（ ）=0.043
430÷（ ）=0.43 10
100
100
1000
10000
1000

17. Fill in ○ with ×、÷ Fill in（ ）with number 3.8○10=38 47○100=0.47
3.8○10= ○100=0.47
○100= ○10= ○1000= ○100=8.4
5.27 ○( )= ○( ) =3.218

18. Fill in ○ with ×、÷ Fill in（ ）with number 3.8○10=38 47○100=0.47
3.8○10= ○100=0.47
○100= ○10= ○1000= ○100=8.4
5.27 ○( )= ○( ) =3.218 × ÷ × ÷ ÷ ×
100
1000 × ÷

19. 3.72 ×23=A
37.2 ×23=B
372 ×23=C
What is the relationship among A,B,C?

20. Thank you!