1. Mentally Multiply & Divide

2. You already do mental math!  123 x 10 =  1,230  123 x 100 =  12,300  123 x 1000 =  123,000 How is it different to do…  12.3 x 10 =  123  12.3 x 100 =  1,230  12.3 x 1000 =  12,300

3. All you do is move the decimal!

4. Working with ‘Big’ Numbers 10, 100, 1000, 10000, …  Multiplying :  Move the decimal point RIGHT the same number of times as there are zeros in the number!  Example: 12.045 x 100 = 1,204.5  Dividing :  Move the decimal point LEFT the same number of times as there are zeros in the number!  Example: 12.045 ÷ 100 = 0.12045

5. Working with ‘Little’ Numbers 0.1, 0.01, 0.001, 0.0001 …  Multiplying :  Move the decimal point LEFT the same number of times as there are digits after the decimal point!  Example: 12.045 x 0.0001 = 0.0012045  Dividing :  Move the decimal point RIGHT the same number of times as there are digits after the decimal point!  Example: 12.045 ÷ 0.01 = 1,204.5

6. Remember: If you multiply by a BIG number, you move to the RIGHT. If you multiply by a LITTLE number, you move to the LEFT. When you divide, everything moves in the OPPOSITE direction.

7. Practice  7,845.2 x 1000 =  7,845,200

8. Practice  7,845.2 ÷ 1000 =  7.8452

9. Practice  7,845.2 ÷ 0.001 =  7,845,200

10. Practice  7,845.2 x 0.1 =  784.52

11. Practice  0.203 ÷ 10 =  0.0203

12. Practice  1900 x 1000 =  1,900,000

13. Practice  700.15 x 0.0001 =  0.070015

14. Practice  0.004 ÷ 0.01 =  0.4

15. Practice  0.0003 x 1000 =  0.3

16. Practice  19 x 0.0001 =  0.0019

17. Practice  100 x 13.52 =  1,352

18. Practice  9,912.78 ÷ 10,000 =  0.991278

19. Exit Ticket 1. 17.5 x 0.001= 2. 10,000 x 0.45 = 3. 945 ÷ 0.01 = 4. 0.045 ÷ 10 = 5. 15.2 x 0.0001=