Multiplication Mrs. Walker 4th Grade

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

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.

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

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

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

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

Commutative Property of Multiplication Lets Practice: 34 x 8 = ____ x 34 5 x ____ = 62 x 5 ____ x 9 = 9 x 71

Associative Property 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)

Associative Property 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

Zero Property of Multiplication Any factor (number) multiplied by 0 will equal 0. Example: 679 x 0 = 0

Zero Property of Multiplication Lets Practice: 43 x 0 = ____ 35 x ____ = 0

Identity Property of Multiplication Any factor (number) multiplied by 1 will equal that number. Example: 679 x 1 = 679

Identity Property of Multiplication Lets Practice: 55 x 1 = ____ 77 x ____ = 77

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)

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)

Multiplication Steps 2 Digit x 1 Digit 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.

2 Digit x 1 Digit 1 2 Start Here

2 Digit x 1 Digit 1 1 2 1 2 5 6

Hand Trick: UP then OVER!

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

Hand Trick: UP then OVER!

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

Hand Trick: UP then OVER!

You Try One… 2 8 4 1 2 6 5 0 4

You Try Another… 7 1 9 8 1 5 2

You Try Another… 3 1 9 2 7 9

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

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

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

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

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

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

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

2 Digit x 2 Digit 1 Step 1: Write the problem making sure you line up the correct place values. 8 3 2 1 2 1 5 2 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. 1 6 6 4 1 5 Step 4: Do the red steps next. 4 , 3 1 6 Step 5: Add the green and red answers together.

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

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 2 8 2 Step 4: Do the red steps next. 3 , 5 7 2 Step 5: Add the green and red answers together.

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

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 1 7 Step 4: Do the red steps next. 2 , 1 2 5 Step 5: Add the green and red answers together.

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 2 3 Step 4: Do the red steps next. 3 2 2 Step 5: Add the green and red answers together.

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 2 9 2 Step 4: Do the red steps next. 3 , 5 4 Step 5: Add the green and red answers together.

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

What do you think the steps will be to multiply a 3 Digit x a 2 Digit? 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

Great Job!