1. Multiplication Multiplying by multiples of 10

2. Multiplying by 10 and 100: Count by each number 5 times. 5 x 1 =5 5 x 10 = 50 5 x 100 =500 5 x 1,000 = 5,000 5 x 10,000 = 50,000 Remember to think of it as 5 groups of ____

3. What will we learn today? Today, instead of counting by equal groups, we will use two strategies to help us multiply. 1: We will use the associate property to make multiplying easier. 2: We will use place value to make multiplying easier.

4. Let’s look at this one: 5 x 40 Think back to the associative property from yesterday….

5. Let’s look at this one: 5 x 40 = 5 x (4 x 10) 40

6. Let’s look at this one: 5 x 40 = (5 x 4) x 10 20

7. Let’s look at this one: 5 x 40 = x 10 20= 200 5 x 40 = 200

8. 60 9 90 120 12 15 150 EngageNY

9. Use what we just learned to solve this with your group…. 20 x 4 = 2 x 10 x 4

10. Use what we just learned to solve this with your group…. 20 x 4 = 2 x 4 x 10

11. Use what we just learned to solve this with your group…. 20 x 4 = (2 x 4) x 10 8

12. Use what we just learned to solve this with your group…. 20 x 4 = 8 x 10

13. Use what we just learned to solve this with your group…. 20 x 4 = 8 x 10 8 x 10 = 10 x 8

14. Let’s look at this one again: 5 x 40 20 With one zero, it’s like multiplying by a 10, or moving the number over one place value from 20 ones to 20 tens. 20 tens = 200!

15. Let’s look at this one again: 5 x 40 = 5 x 4tens 20 tens With one zero, it’s like multiplying by a 10, or moving the number over one place value from 20 ones to 20 tens. 20 tens = 200!

16. Here’s another example… 12 120

17. EngageNY 8 8 8 80 15 150 You try!

18. Use what we just learned to solve this with your group…. 20 x 4 = 2 tens x 4 = 8 tens = 80 3 x 80 = 3 x 8 tens = 24 tens = 240

20. Let’s look at multiplying by multiples of 10 again.

21. By the end of this lesson, you will be able to answer this problem! 50 x 400

22. Let’s look a little closer at what we saw earlier…Do you notice a pattern? 5 x 1 =5 5 x 10 = 50 5 x 100 =500 5 x 1,000 = 5,000 5 x 10,000 = 50,000

23. Let’s look at this one yet again… 5 x 40 200 20

24. Here’s what you should know…. You can use the associative property: 5 x 60 = 5 x (6 x 10)

25. Here’s what you should know…. You can use the associative property: 5 x 60 = (5 x 6) x 10

26. Here’s what you should know…. You can use the associative property: 5 x 60 = (5 x 6) x 10 = 30 x 10

27. Here’s what you should know…. You can use the associative property: 5 x 60 = (5 x 6) x 10 = 30 x 10 = 300 When you multiply by 10, you move it to the left one place value.

28. Here’s what you should know…. You can use the associative property: 5 x 60 = (5 x 6) x 10 = 30 x 10 = 300 When you multiply by 10, you move it to the left one place value. When you multiply by 100, you move it over 2 place values. 30 x 100 = 3,000

29. Here’s what you should know…. You can use the associative property: 5 x 60 = (5 x 6) x 10 = 30 x 10 = 300 When you multiply by 10, you move it to the left one place value. When you multiply by 100, you move it over 2 place values. What do you think happens when you multiply by 1,000? 10,000? 30 x 1,000 = 30,000 30 x 100 = 3,000 30 x 10,000 = 300,000

30. Here’s what you should know…. You can use the associative property: 5 x 60 = (5 x 6) x 10 = 30 x 10 = 300 When you multiply by 10, you move it to the left one place value. When you multiply by 100, you move it over 2 place values. If you know this, you can take the shortcut! 1: Find your basic fact and multiply. 2: Count the number of zeros in the factors. 3: Add the same number of zeros to the product!

31. Multiplying by 10 and 100 50 x 3 = 150 50 x 30 = 1,500 500 x 30 = 15,000 500 x 300 = 150,000 5 x 3 = 15

32. What do you think we will do here? 5 X 4 5 x 4

33. What do you think we will do here? 5 X 4 5 x 4 = 20

34. What do you think we will do here? 5 X 4 5 x 4 = 20

35. What do you think we will do here? 5 X 4 5 x 4 = 20

36. What do you think we will do here? 200,000 50 x 4,000

37. You try! 40 x 100

38. What do you think we will do here? 4 X 1 4 x 1 =

39. What do you think we will do here? 4 X 1 4 x 1 = 4

40. What do you think we will do here? 4 X 1 4 x 1 = 4

41. What do you think we will do here? 4 X 1 4 x 1 = 4

42. What do you think we will do here? 4 X 1 4 x 1 = 4,000

43. You try! 400 x 200

44. You try! 400 x 200 8

45. You try! 400 x 200 80000

46. You try! 400 x 200 80,000

47. What do you think? 60 x 300 18,000

48. Try all 4 on your board 9 x 400 1 x 70,000 60 x 900 200 x 9,000

49. Try all 4 on your board 9 x 400 1 x 70,000 60 x 900 200 x 9,000 3,600 70,000 54,000 1,800,000

50. How do you feel? Use your sticker chart to show me how you feel about multiplication with zeros?

51. Great job!