Multiply a decimal by 10, 100, 1000,..
1.1. Knowledge to remember
a) Example 1: 27,867 x 10 = ?
27.867 x 10 = 278.67
Comment: If we move the comma of the number 27,867 one digit to the right, we also get 278.67.
b) Example 2: 53.286 x 100 = ?
53.286 x 100 = 5328,600
Comment: If we move the comma of the number 53.286 to the right by two digits, we also get 5328.6.
To multiply a decimal number by 10,100,1000.., we just need to move the comma of that number to the right one, two, three… digits respectively.
1.2. Solve textbook exercises page 57
Lesson 1 Textbook page 57
a) 1.4×10 b) 9.63×10
Lesson 2 Textbook page 57
Write the following measurements as centimeters:
10.4dm; 12.6m; 0.856m; 5.75dm.
+ 1dm = 10cm so 10.4dm = 10cm x 10.4 = 104cm.
+ 1m = 100cm so 12.6m = 100cm x 12.6 = 1260cm;
+ 1m = 100cm so 0.856m = 100cm x 0.856 = 85.6cm;
+ 1dm = 10cm so 5.75dm = 10cm x 5.75 = 57.5cm
Lesson 3 Textbook page 57
A plastic can contains 10 liters of kerosene. Know the weight of a liter of kerosene
, empty can weigh cân
. How many kilograms does that can of kerosene weigh?
kerosene weighing kilograms is:
That whole can of kerosene weighs kilograms:
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