Multiplication

1. Multiplication Mrs. Walker 4th Grade

2. Objective: • Today will learn how to multiply numbers with 2 digits by numbers with 1 digit. Example: 34 x 9

3. Why do we need to know the Multiplication Properties? • It helps you solve problems without working them out. • It helps with mental math. • It makes understanding math easier.

4. Vocabulary To Know: • Factor • Product • Commutative Property • Associative Property • Identity Property • Zero Property • Distributive Property

5. Factor • The numbers that are multiplied together in a multiplication problem. Example: 34 x 9 = 306

6. Product • The answer to a multiplication problem. Example: 34 x 9 = 306

7. CommutativeProperty of Multiplication • The order that factors (numbers) are multiplied will not change the product (answer). Example: 56 x 4 = 4 x 56

8. CommutativeProperty of Multiplication Lets Practice: • 34 x 8 = ____ x 34 • 5 x ____ = 62 x 5 • ____ x 9 = 9 x 71

9. AssociativeProperty of Multiplication • The way that factors (numbers) are grouped will not change the product (answer). Example: (21 x 3) x 9 = 21 x (3 x 9)

10. AssociativeProperty of Multiplication Lets Practice: • 34 x (___ x 6) = (34 x 8) x 6 • (431 x 6) x 3 = ___ x (6 x 3) • 19 x (___ x ___) = (19 x 2) x 7

11. ZeroProperty of Multiplication • Any factor (number) multiplied by 0 will equal 0. Example: 679 x 0 = 0

12. ZeroProperty of Multiplication Lets Practice: • 43 x 0 = ____ • 35 x ____ = 0

13. IdentityProperty of Multiplication • Any factor (number) multiplied by 1 will equal that number. Example: 679 x 1 = 679

14. IdentityProperty of Multiplication Lets Practice: • 55 x 1 = ____ • 77 x ____ = 77

15. Distributive Property of Multiplication • When two addends are multiplied by a factor the product will be the same as when each addend is multiplied by the factor and the products are added. Example: (2 + 3) x 4 = (2 x 4) + (3 x 4)

16. Distributive Property of Multiplication Lets Practice: • (2 + 6) x 34 = (___ x 34) + (___ x 34) • (6 + 9) x 16 = (___ x 16) + (___ x 16) • (4 + 5) x 23 = (4 x ___) + (5 x ___) • (___ + 3) x 11 = (7 x 11) + (3 x 11) • (___ + ___) x 90 = (4 x 90) + (1 x 90)

17. 2 Digit x 1 Digit Multiplication Steps • Write the problem – lining up the place values (ones under ones). • Multiply the bottom number in the ones place by the top number in the ones place. • Write the answer below the problem in the ones place. Regroup if necessary. • Multiply the bottom number in the ones place by the top number in the tens place and add the number you carried if you have one. • Write the answer below the problem in the tens place.

18. 2 Digit x 1 Digit 2 1 Start Here

19. 2 Digit x 1 Digit 1 1 2 2 1 5 6 0

20. Hand Trick: UP then OVER!

21. 2 Digit x 1 Digit 1 6 3 2 1 4 2 5 2

22. Hand Trick: UP then OVER!

23. 2 Digit x 1 Digit 6 9 9 2 1 7 6 9 3

24. Hand Trick: UP then OVER!

25. You Try One… 2 8 4 2 1 6 5 0 4

26. You Try Another… 7 1 9 8 1 5 2

27. You Try Another… 3 1 9 2 7 9

28. 3Digit x 1 Digit 1 2 1 2 1 3 2 1 3 5 1 0 6 0 ,

29. 3Digit x 1 Digit 1 2 6 3 9 1 3 2 1 3 3 1 9 1 7 ,

30. 2 & 3 Digit x 1Digit Independent Practice • 28 x 1 = • 26 x 3 = • 343 x 6 = • 54 x 8 = • 414 x 3 = • 14 x 5 = • 62 x 2 = • 234 x 9 = • 45 x 7 = • 87 x 4 =

31. 2 Digit x 2 Digit Steps Step 1: Write the problem making sure you line up the correct place values. 1 Step 2: Do the green steps first. 2 2 1 Start Here Start Here Step 3: Mark out the number you carried and add a zero to hold the ones place. 0 Step 4: Do the red steps next. Step 5: Add the green and red answers together.

32. UP then OVER and OVER then UP! Hand Trick:

33. 1 2 Digit x 2 Digit 1 Step 1: Write the problem making sure you line up the correct place values. 4 6 1 2 3 Step 2: Do the green steps first. 2 2 1 Step 3: Mark out the number you carried and add a zero to hold the ones place. 1 3 8 0 9 2 Step 4: Do the red steps next. 1 0 8 , 5 Step 5: Add the green and red answers together.

34. UP then OVER and OVER then UP! Hand Trick:

35. 2 Digit x 2 Digit 1 Step 1: Write the problem making sure you line up the correct place values. 8 3 1 5 2 Step 2: Do the green steps first. 2 2 1 1 Step 3: Mark out the number you carried and add a zero to hold the ones place. 1 6 6 0 4 1 5 Step 4: Do the red steps next. 4 3 6 , 1 Step 5: Add the green and red answers together.

36. UP then OVER and OVER then UP! Hand Trick:

37. 1 2 Digit x 2 Digit 3 Step 1: Write the problem making sure you line up the correct place values. 9 4 3 8 Step 2: Do the green steps first. Step 3: Mark out the number you carried and add a zero to hold the ones place. 7 5 2 1 0 2 8 2 Step 4: Do the red steps next. 5 2 3 , 7 Step 5: Add the green and red answers together.

38. UP then OVER and OVER then UP! Hand Trick:

39. 1 2 Digit x 2 Digit 2 Step 1: Write the problem making sure you line up the correct place values. 8 5 2 5 Step 2: Do the green steps first. Step 3: Mark out the number you carried and add a zero to hold the ones place. 4 2 5 1 0 1 7 0 Step 4: Do the red steps next. 1 5 2 , 2 Step 5: Add the green and red answers together.

40. You try one… 1 Step 1: Write the problem making sure you line up the correct place values. 2 3 1 4 Step 2: Do the green steps first. Step 3: Mark out the number you carried and add a zero to hold the ones place. 9 2 1 0 2 3 Step 4: Do the red steps next. 3 2 2 Step 5: Add the green and red answers together.

41. 1 You try another… 2 Step 1: Write the problem making sure you line up the correct place values. 7 3 4 8 Step 2: Do the green steps first. 1 Step 3: Mark out the number you carried and add a zero to hold the ones place. 5 8 4 1 0 2 9 2 Step 4: Do the red steps next. 5 4 3 , 0 Step 5: Add the green and red answers together.

42. 2 Digit x 2 Digit Independent Practice • 28 x 12 = • 26 x 37 = • 43 x 62 = • 54 x 86 = • 44 x 38 = • 26 x 35 = • 62 x 41 = • 34 x 99 = • 45 x 74 = • 87 x 73 =

43. 3 Digit x 2 Digit What do you think the steps will be to multiply a 3 Digit x a 2 Digit? 548 x 19 423 x 25 937 x 62

44. Great Job!