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Multiplying and Dividing Multiplying and Dividing Decimals By Powers of 10.Decimals By Powers of 10.Multiplying and Dividing Multiplying and Dividing
Decimals By Powers of 10.Decimals By Powers of 10.
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Multiplying by Powers of 10Multiplying by Powers of 10
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Warm-upWarm-up 5.3 x 9 =47.75.3 x 9 =47.7 7.2 ÷ 0.4=18 7.2 ÷ 0.4=18 7 x 8.39 =58.737 x 8.39 =58.73 0.006 ÷ 0.3 =0.020.006 ÷ 0.3 =0.02 9.7 x 0.8 =7.769.7 x 0.8 =7.76 1.8 x 1.23 =2.2141.8 x 1.23 =2.214 2.9 x 0.06= 0.1742.9 x 0.06= 0.174 90.3 ÷ 6=15.0590.3 ÷ 6=15.05 246.5 ÷ .2465=1000246.5 ÷ .2465=1000
Practice it
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Multiplying by 10Multiplying by 10
Multiplying by 10 moves the Multiplying by 10 moves the decimal point one place to the decimal point one place to the right.right.
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ExamplesExamples
10 10 x 0.389 = 03.89x 0.389 = 03.89 10 10 x 3.89 = 38.9x 3.89 = 38.9 10 10 x 38.9 = 389x 38.9 = 389
0 . 3 893. 8 9
38. 9
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ProblemsProblems 10 x 5.623 =56.23
0.1 x 10 =1
0.001 x 10 =0.01
0.01 x 10 =0.1
7.8 x 10 =78
28.256 x 10 =282.56
19.52 x 10=195.2
Look for a pattern.
Watch the decimal points.
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Multiplying by 100Multiplying by 100
Multiplying by 100 moves Multiplying by 100 moves the decimal point the decimal point two places to the right.places to the right.
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ExamplesExamples
100 x 0.795 = 79.5100 x 0.795 = 79.5 100 x 7.95 = 795100 x 7.95 = 795 100 x 79.5 = 7950100 x 79.5 = 7950
0. 79 57. 95
79.50 Extra zero
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LET’S PRACTICELET’S PRACTICE O.2 X 100 =20
0.02 X 100 =2
0.002 X 100 =0.2
7.8 X 100 =780
19.52 X 100 =1952
28.256 X 100 =2825.6
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MULTIPLYING BY MULTIPLYING BY 10001000
MULTIPLYING BY 1000 MOVES MULTIPLYING BY 1000 MOVES THE DECIMAL POINT THE DECIMAL POINT THREE THREE PLACES TO THE RIGHT.PLACES TO THE RIGHT.
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EXAMPLES:EXAMPLES:
1000 X 2.359 = 23591000 X 2.359 = 2359
1000 X 23.59 = 235901000 X 23.59 = 23590
2. 3 5 9
23. 590 EXTRA ZERO
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PROBLEMSPROBLEMS
28.256 X 1000 =28,256 19.52 X 1000 =19520
7.8 X 1000 =7800
0.3 X 1000 =300
0.03 X 1000 =30
0.003 X 1000=3
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BreakBreak
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DIVIDING BY POWERS OF DIVIDING BY POWERS OF 1010
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DIVISION BY 10, 100, 1000DIVISION BY 10, 100, 1000
WHEN DIVIDING BYWHEN DIVIDING BY THE DECIMAL POINT THE DECIMAL POINT MOVES TO THE LEFT MOVES TO THE LEFT BYBY
1010 1 DECIMAL PLACE1 DECIMAL PLACE
100100 2 DECIMAL PLACES2 DECIMAL PLACES
10001000 3 DECIMAL PLACES3 DECIMAL PLACES
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EXAMPLESEXAMPLES
a)a) 321.5 ÷ 321.5 ÷ 10 10 = 32.15= 32.15
b)b) 321.5 ÷ 321.5 ÷ 100 100 = 3.215= 3.215
c)c) 321.5 ÷ 321.5 ÷ 1000 1000 = = 0.32150.3215
321.5
321.5
321.5
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ProblemsProblems 4 ÷ 10 =0.4 2.35 ÷ 100=0.02350 0.288 ÷ 100 =0.00288 357 ÷ 1000 =0.357 243 ÷ 100000
=0.00243
6.3 ÷ 10=0.63
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Just try this!!!Just try this!!!
http://www.jigzone.com/puzzles/A7055D506E99?z=10
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Mixed PracticeMixed Practice
5.3 x 100 =530 0.84 x 10 =8.4 17.42 x 1000 =17420 1.235 x 100000 =123500 0.00007 x 1000000 =70
4.35 ÷ 100=0.0435
21.5 ÷ 10 =2.15
8.79 ÷ 10000=0.000879
0.0594 ÷ 1000=0.0000594
0.27222÷10000=.000027222
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ReviewReview
Multiplying by powers of 10 shifts the decimal places to the right of the decimal in the question according to the number of zeroes in the powers of 10.
Dividing by powers of 10 moves the decimal places to the left of the decimal in the question according to the number of zeroes in the powers of 10.
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