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Lisa_multiplying and dividing by 10,100

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Information about Lisa_multiplying and dividing by 10,100
Education

Published on December 1, 2008

Author: lisamahon

Source: authorstream.com

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Slide 1: Multiplying and Dividing decimals by 10’s, 100’s, 1000’s etc By Lisa Mahon Slide 2: Multiplying whole numbers by 10’s, 100’s, 1000’s etc 1 x 10 = 10 5 x 10 = 50 12 x 10 = 120 135 x 10 = 1350 What do you notice about each new answer? Quick method : add a zero to the end of the whole number when multiplying by 10 Multiplying a whole number by 10 A zero is added to the end of the number Slide 3: What would you do if you multiplied by 100? 1 x 100 = 100 5 x 100 = 500 12 x 100 = 1200 135 x 100 = 13500 Quick method : add a zero to the end of the whole number for each multiply of 10 x 10 add 1 zero x 100 add 2 zero x 1000 add 3 zero etc Slide 4: Multiplying decimals by 10’s 1.5 x 10 = 15 1.23 x 10 = 12 3 Each zero represents one movement of the decimal place to the right. . . 0.5 x 10 = 5 13.23 x 10 = 132 3 . . If decimal point lands at the end you do not have to write it in Remember, if decimal point lands at the end you do not have to write it in Slide 5: Multiplying decimals by 100’s 1.56 x 100 = 156 51.234 x 100 = 5123 4 Each zero represents one movement of the decimal place to the right, thus 2 movements to the right . . 0.5 x 100 = 13.23 x 100 = 1323 . . If decimal point lands at the end you do not have to write it in Remember, if decimal point lands at the end you do not have to write it in Don’t forget to add an extra zero 50 Slide 6: Dividing decimals by 10’s 1.5  10 = 12.3  10 = Each zero represents one movement of the decimal place to the left . 0.5  10 = 1323  10 = . If decimal point lands at the beginning add a zero in front If decimal point lands at the beginning add a zero in front 0 15 1.23 05 0 . Remember, there is a decimal point at the end of the number 132 3 Slide 7: Dividing decimals by 100’s 1.5  100 = 12.3  100 = Each zero represents one movement of the decimal place to the left . 321.5  100 = 1323  100 = . If decimal point lands at the beginning add a zero in front 0 15 123 3 215 . Remember, there is a decimal point at the end of the number 13 23 0 . 0

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