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The ideas in this multiplication lesson are taken from Division 2 ebook. Only a few examples of each problem type are shown; you should make more problems of each kind for the student. Multiplying by whole tens - by 10, 20, 30 etc.
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| 9 × 10 = ___
10 × 10 = ___ 11 × 10 = ___ 12 × 10 = ___ 13 × 10 = ___ |
14 × 10 = ___
15 × 10 = ___ 16 × 10 = ___ 17 × 10 = ___ 18 × 10 = ___ |
19 × 10 = ___ 20 × 10 = ___ 21 × 10 = ___ 22 × 10 = ___ 23 × 10 = ___ |
24 × 10 = ___ 25 × 10 = ___ 26 × 10 = ___ 27 × 10 = ___ 28 × 10 = ___ |
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What pattern do you see? |
Since multiplication can be done in any order one wishes, or 25 ×
10 = 10 × 25, this rule/pattern works in either case.
Example problems
1. Multiply.
| 10 × 11 = ___
56 × 10 = ___ 10 × 98 = ___ 12 × 7 = ___ 20 × 10 = ___ |
18 × 10 = ___
10 × 10 = ___ 10 × 0 = ___ 9 × 8 = ___ 77 × 10 = ___ |
10 × 5 = ___
97 × 10 = ___ 10 × 82 = ___ 9 × 9 = ___ 2 × 10 = ___ |
| Note that 20 = 10 × 2. We can use that to multiply by 20.
For example,
20 × 11 = 10 × 2 × 11 Now multiply first 2 × 11 = 22. Then use the easy rule for multiplying by ten: 10 × 2 × 11 = 10 × 22 = 220. So we have 20 × 11 = 220. |
1. Multiply by 20. First break 20 down into 10 ×
2.
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| What is the easy rule for multiplying by 20? |
| Note that 30 = 10 × 3. We can use that to multiply by 30.
For example,
30 × 9 = 10 × 3 × 9 = 10 × 3 × 9 = 10 × 27 = 270 Note that 50 = 10 × 5. We can use that to multiply by 50. For example,50 × 7 = 10 × 5 × 7 = 10 × 5 × 7 = 10 × 35 = 350 Note that 80 = 10 × 8. We can use that to multiply by 80. For example,80 × 6 = 10 × 8 × 6 = 10 × 8 × 6 = 10 × 48 = 480. |
2. Multiply. First break 20, 30, 40, etc down into 10 × a number.
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Write down here the results from the last exercise:
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3. Multiply.
| a. | d. |
| 40 × 5 = ____
8 × 20 = ____ 7 × 70 = ____ 30 × 4 = ____ 3 × 40 = ____ 70 × 4 = ____ |
70 × 11 = ____
6 × 40 = ____ 12 × 30 = ____ 8 × 80 = ____ 11 × 40 = ____ 4 × 50 = ____ |
4. For each multiplication, write two division sentences.
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d. 3 × 30 = | ||||
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e. 7 × 40 =
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h. 9 × 60 = |
5. Divide. Think backwards of the multiplication rules you've learned
in this lesson.
| a. 120 × 10 = | c. 100 × 10 = | d. 200 × 10 = |
| i. 120 × 20 = | k. 120 × 60 = | l. 180 × 60 = |
| m. 160 × 40 = | o. 560 × 70 = | p. 420 × 60 = |
6. Continue the patterns.
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a. 100 × 10 = 200 × 10 = 300 × 10 = 400 × 10 =
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d. 100 × 50 = 150 × 50 = 200 × 50 = 250 × 50 = |
The fast, FUN, and easy way to learn multiplication. Learn the upper times tales in two sittings using mnemonic stories.
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Copyright 2003-2012 Maria Miller
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