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I. Multiplication of a decimal number by a whole number
1. product and factors
Multiplication is the operation that calculates the product of two numbers.
Each number that is multiplied is called the factor of the product.
Example:
4,2 and 3 are the factors and 12.6 is the product.
To calculate the product of two factors, we can:
- change the order of the factors;
- group the factors differently.
Examples:
2. Multiply by 10, 100, 1000
When you multiply a number :
- by 10, the units digit becomes the tens digit;
- by 100, the units digit becomes the hundreds digit;
- by 1,000, the number of units becomes the number of thousands.
Example:
3. operating technique
To multiply a decimal number by a whole number :
- we start the calculations on the right, without taking into account the decimal point;
- the same number of digits after the decimal point is placed in the result as in the decimal number.
Example:
II. Multiplication of two decimal numbers
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Multiplication by 0.1; 0.01; 0.001
When you multiply a number :
- by 0.1, the units digit becomes the tenths digit;
- by 0.01, the units digit becomes the hundredths digit;
- by 0.001, the units digit becomes the thousandths digit.
Example:
2.Operating technique
To perform a multiplication of two decimal numbers :
- it is first performed without taking commas into account;
- the same number of digits after the decimal point as the total number of digits after the decimal point in the two factors is placed in the result.
Example:
To get an order of magnitude of a product, we multiply an order of magnitude of each of the factors.
Example:
An order of magnitude of 1.95 is 2.
An order of magnitude of 4.2 is 4; therefore an order of magnitude of is
or 8.
3. operating priorities
- Calculations in parentheses take precedence;
- Multiplication takes precedence over addition and subtraction.
Examples:
Have you assimilated the multiplication course in 6th grade?
QCM de maths sur la multiplication en 6ème.
Skills to learn about multiplication:
- Know the definition of a product and a factor;
- Know how to multiply in rows and columns;
- Know how to multiply by 10, 100, 1000, 0.1, 0.01, 0.001, etc.
- Give an order of magnitude of a product;
This course is in accordance with the official programs of thenational education.
In addition, you can continue with the exercises on the 4 operations in the sixth grade.
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