Chapter 4
Multiplication Strategies
Multiplication Strategies
To multiply by 2's:
Double the number being multiplied by 2.
Ex:
2 x 7 =
7 + 7 = 14
Double the number being multiplied by 2.
Ex:
2 x 7 =
7 + 7 = 14
To multiply by 4's:
First
Use the 2's multiplication facts to help. If you have 4 x 7, this is 4 groups of 7. |
Second
You know what 2 x 7, this is 2 groups of 7. 2 x 7 = 14 |
Third
Double 14 to get 4 groups of 7 instead of 2 groups. 14 + 14 = 28 |
To multiply by 5's:
Simply skip count by 5's. Ex: 5 x 9 = 5, 10, 15, 20, 25, 30, 35, 40, 45 Thus 5 x 9 = 45 |
To multiply by 10's:
Simply skip count by 10's. Ex: 10 x 8 = 10, 20, 30, 40, 50, 60, 70, 80 Thus 10 x 8 = 80 |
To multiply by 3's:
Simply skip count by 3's.
Ex:
3 x 7 =
3, 6, 9, 12, 15, 18, 21
Simply skip count by 3's.
Ex:
3 x 7 =
3, 6, 9, 12, 15, 18, 21
To multiply by 6's:
Ex:
6 x 8 =
This is six groups of eight
Instead do five groups of eight
5 x 8 = 40
Then add the additional group of 8
(5 x 8) + 8 =
40 + 8 = 48
Ex:
6 x 8 =
This is six groups of eight
Instead do five groups of eight
5 x 8 = 40
Then add the additional group of 8
(5 x 8) + 8 =
40 + 8 = 48
To multiply by 7's:
To multiply by 8's:
First
Use the 4's multiplication facts to help. If you have 8 x 7, this is 8 groups of 7. |
Second
You know what 4 x 7, this is 4 groups of 7. 4 x 7 = 28 |
Third
Double 28 to get 8 groups of 7 instead of 4 groups. 28 + 28 = 56 |
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To multiply by 9's:
9 x 1 = 09 (0 + 9 = 9)
9 x 2 = 18 (1 + 8 = 9) 9 x 3 = 27 (2 + 7 = 9) 9 x 4 = 36 (3 + 6 = 9) 9 x 5 = 45 (4 + 5 = 9) 9 x 6 = 54 (5 + 4 = 9) 9 x 7 = 63 (6 + 3 = 9) 9 x 8 = 72 (7 + 2 = 9) 9 x 9 = 81 (8 + 1 = 9) |
Rule #1: Look at the number being multiplied by 9. Make that number 1 less and write the digit down.
Rule #2: To get the product, the second digit is found by finding what needs to be added to the first digit to equal 9. Example: 9 x 6 = 1 less than 6 is 5, thus five is the 1st digit Then 4 + 5 = 9, thus 4 is the 2nd digit. Final product is first digit next to the second digit 54 |
Use the file below to practice your time tables.
Times Table Challenge.pdf | |
File Size: | 1367 kb |
File Type: |
Below are the jeopardy games we play in class for each chapter.
Use for studying purposes.
Use for studying purposes.