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Multiplication Properties - Teacher

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									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:
1. 34 x 8 = ____ x 34
2. 5 x ____ = 62 x 5
3. ____ 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:
 1. 34 x (___ x 6) = (34 x 8) x 6
 2. (431 x 6) x 3 = ___ x (6 x 3)
 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:
1. 43 x 0 = ____
2. 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:
1. 55 x 1 = ____
2. 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:
1. (2 + 6) x 34 = (___ x 34) + (___ x 34)
2. (6 + 9) x 16 = (___ x 16) + (___ x 16)
3. (4 + 5) x 23 = (4 x ___) + (5 x ___)
4. (___ + 3) x 11 = (7 x 11) + (3 x 11)
5. (___ + ___) x 90 = (4 x 90) + (1 x 90)
                         2 Digit x 1 Digit
       Multiplication Steps
1. Write the problem – lining up the place
   values (ones under ones).
2. Multiply the bottom number in the ones
   place by the top number in the ones place.
3. Write the answer below the problem in the
   ones place. Regroup if necessary.
4. 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.
5. Write the answer below the problem in the
   tens place.
 2 Digit x 1 Digit




2      1
 Start
 Here
    2 Digit x 1 Digit

1
1       2
    2       1
        5
6       0
      Hand Trick:

UP then OVER!
      2 Digit x 1 Digit

 1
 6        3
      2       1
          4
2 5       2
      Hand Trick:

UP then OVER!
      2 Digit x 1 Digit

  6
  9       9
      2       1
          7
6 9       3
      Hand Trick:

UP then OVER!
      You Try One…

  2
  8       4
      2       1
          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
           3 2 1
               1
            5
1, 0   6    0
           3 Digit x 1 Digit

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



Independent Practice
1. 14 x 5 =    6. 28 x 1 =
2. 62 x 2 =    7. 26 x 3 =
3. 234 x 9 =   8. 343 x 6 =
4. 45 x 7 =    9. 54 x 8 =
5. 87 x 4 =    10. 414 x 3 =
                    2 Digit x 2 Digit Steps
                       Step 1: Write the
                       problem making sure
                       you line up the correct
                       place values.
2     1   2     1      Step 2: Do the green
 Start     Start
          Here
                       steps first.
 Here
                       Step 3: Mark out the
                       number you carried
                       and add a zero to hold


           0
                       the ones place.
                       Step 4: Do the red
                       steps next.
                       Step 5: Add the green
                       and red answers
                       together.
        Hand Trick:
UP then OVER and
  OVER then UP!
     1              2 Digit x 2 Digit
     1               Step 1: Write the
                     problem making sure
     4      6        you line up the correct
                     place values.

     2      3
    2   1   2   1    Step 2: Do the green
                     steps first.
                     Step 3: Mark out the

   1 3      8        number you carried
                     and add a zero to hold


            0
                     the ones place.
   9 2               Step 4: Do the red
                     steps next.

1, 0 5      8        Step 5: Add the green
                     and red answers
                     together.
        Hand Trick:
UP then OVER and
  OVER then UP!
                     2 Digit x 2 Digit
     1                Step 1: Write the
                      problem making sure
     8       3        you line up the correct
                      place values.

     5       2
    2    1   2   1    Step 2: Do the green
                      steps first.
   1                  Step 3: Mark out the

   1 6       6        number you carried
                      and add a zero to hold


             0
                      the ones place.
4 1 5                 Step 4: Do the red
                      steps next.

4, 3 1       6        Step 5: Add the green
                      and red answers
                      together.
        Hand Trick:
UP then OVER and
  OVER then UP!
     1       2 Digit x 2 Digit
     3        Step 1: Write the
              problem making sure
     9   4    you line up the correct
              place values.

     3   8
              Step 2: Do the green
              steps first.
              Step 3: Mark out the


1
   7 5   2    number you carried
              and add a zero to hold


         0
              the ones place.
2 8 2         Step 4: Do the red
              steps next.

3, 5 7   2    Step 5: Add the green
              and red answers
              together.
        Hand Trick:
UP then OVER and
  OVER then UP!
     1       2 Digit x 2 Digit
     2        Step 1: Write the
              problem making sure
     8   5    you line up the correct
              place values.

     2   5
              Step 2: Do the green
              steps first.
              Step 3: Mark out the


1
   4 2   5    number you carried
              and add a zero to hold


         0
              the ones place.
1 7 0         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
  2   3    you line up the correct
           place values.

  1   4
           Step 2: Do the green
           steps first.
           Step 3: Mark out the


1
  9   2    number you carried
           and add a zero to hold


      0
           the ones place.
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
     7   3     you line up the correct
               place values.

     4   8
               Step 2: Do the green
               steps first.
   1           Step 3: Mark out the


1
   5 8   4     number you carried
               and add a zero to hold


         0
               the ones place.
2 9 2          Step 4: Do the red
               steps next.

3, 5 0   4     Step 5: Add the green
               and red answers
               together.
               2 Digit x 2 Digit


Independent Practice
1. 26 x 35 =   6. 28 x 12 =
2. 62 x 41 =   7. 26 x 37 =
3. 34 x 99 =   8. 43 x 62 =
4. 45 x 74 =   9. 54 x 86 =
5. 87 x 73 =   10. 44 x 38 =
                  3 Digit x 2 Digit

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


 548          423           937
x 19         x 25          x 62
Great Job!

								
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