This document discusses multiplying and dividing by powers of ten. [1] It provides examples of multiplying and dividing whole numbers and decimals by powers of ten and explains the rules for moving the decimal place. [2] Students are instructed to copy the rules in their notebooks and work through sample problems applying the rules. [3] They are also given homework problems to work through applying multiplying and dividing decimals by powers of ten.

1. 4.5 Multiplying And
Dividing by Powers
of Ten
October 21, 2010

2. What happens when you multiply
by powers of ten?
Fill in the blanks below (in your
notebook).
Whole Number Powers of Ten Decimal Powers of Ten
10 x 8.3 = _____ 0.1 x 8.3 = _____
100 x 8.3 = _____ 0.01 x 8.3 = _____
1000 x 8.3 = _____ 0.001 x 8.3 = _____
10,000 x 8.3 = _____ 0.0001 x 8.3 = _____

3. What happens when you multiply
by powers of ten?
Check your answers (in your
notebook).
Whole Number Powers of Ten Decimal Powers of Ten
10 x 8.3 = 83 0.1 x 8.3 = 0.83
100 x 8.3 = 830 0.01 x 8.3 = 0.083
1000 x 8.3 = 8,300 0.001 x 8.3 = 0.0083
10000 x 8.3 = 83,000 .0001 x 8.3 = .00083

4. Multiplying by
Powers of Ten

5. Multiplying by
Powers of Ten
***Copy this in your notebook:

6. Multiplying by
Powers of Ten
***Copy this in your notebook:
Multiplying by whole number powers of 10: Move the
decimal point one place to the right for each zero in
the whole number power 10.

7. Multiplying by
Powers of Ten
***Copy this in your notebook:
Multiplying by whole number powers of 10: Move the
decimal point one place to the right for each zero in
the whole number power 10.
Numbers 3.995 x 100 = 3.99.5

8. Multiplying by
Powers of Ten

9. Multiplying by
Powers of Ten
***Copy this in your notebook:

10. Multiplying by
Powers of Ten
***Copy this in your notebook:
Multiplying by decimal number powers of 10: Move
the decimal point one place to the left for each
decimal place in the whole number power 10.

11. Multiplying by
Powers of Ten
***Copy this in your notebook:
Multiplying by decimal number powers of 10: Move
the decimal point one place to the left for each
decimal place in the whole number power 10.
Numbers 399.5 x 0.001 = 399.5

12. Try these on your own (in
your notebook)
Multiply decimals using mental maths:
0.05 x 1000 =
95.38 x 0.0001

13. Check your answer (in
your notebook)

14. Check your answer (in
your notebook)
Multiply decimals using mental maths:

15. Check your answer (in
your notebook)
Multiply decimals using mental maths:
0.05 x 1000 = 50

16. Check your answer (in
your notebook)
Multiply decimals using mental maths:
0.05 x 1000 = 50
Move the decimal 3 places to the right.

17. Check your answer (in
your notebook)
Multiply decimals using mental maths:
0.05 x 1000 = 50
Move the decimal 3 places to the right.
95.38 x 0.0001 = 0.009538

18. Check your answer (in
your notebook)
Multiply decimals using mental maths:
0.05 x 1000 = 50
Move the decimal 3 places to the right.
95.38 x 0.0001 = 0.009538
Move the decimal 4 places to the left.

19. Dividing by Powers
of Ten

20. Dividing by Powers
of Ten
*** Copy this in your notebook.

21. Dividing by Powers
of Ten
*** Copy this in your notebook.
Dividing by Whole Number Powers of 10: Move the
decimal point one place to the left for each zero in the
whole number power of 10.

22. Dividing by Powers
of Ten
*** Copy this in your notebook.
Dividing by Whole Number Powers of 10: Move the
decimal point one place to the left for each zero in the
whole number power of 10.
35 ÷ 100 = 0.35. = 0.35

23. Dividing by Powers
of Ten

24. Dividing by Powers
of Ten
*** Copy this in your notebook.

25. Dividing by Powers
of Ten
*** Copy this in your notebook.
Dividing by Decimal Number Powers of 10: Move the
decimal point one place to the right for each decimal
place in the whole number power of 10.

26. Dividing by Powers
of Ten
*** Copy this in your notebook.
Dividing by Decimal Number Powers of 10: Move the
decimal point one place to the right for each decimal
place in the whole number power of 10.
35 ÷ 0.01 = 35.00 = 3,500

27. Divide Decimals Using Mental
Math (Now you try: in your
notebook)
• 508.3 ÷ 10
• 508.3 ÷ 0.01

28. Divide Decimals Using Mental
Math (Now you try: in your
notebook)
• 508.3 ÷ 10 = 50.83
Move 1 place to the left.
• 508.3 ÷ 0.01 = 50,830
Move 2 places to the right.

29. Try these (show these problems tomorrow with
your homework)
• 6.07 X 1000
• 153.6 X 0.01
• 42.6 ÷ 100
• 509 ÷ 1000
• 5 ÷ 0.1
• 3.2 ÷ 0.001

30. When you finish:
• You may begin your homework.