The multiplication of integers
Operations with integers II
 
1-a . The multiplication of integers .

When dealing with natural numbers, we know that multiplication is a repeated sum; we add the first number up to itself as many times as indicated by the second number.
But with integers we also have to take the symbol into account. Multiplying a number by a negative number is a repeated sum of the opposite of the first number.

In this window you can modify the values of the first and the second factor, even if  they are negative values, between +9 and -9.
You will find out that the symbol of the product satisfies this rule:
  Esta unidad interactiva requiere la máquina virtual de Java J2RE.

(+) · (+) = +

(+) · (-) = -

(-) · (+) = -

(-) · (-) = +

The product of two numbers with the same symbol is a positive number.

The product of two numbers with a different symbol is a negative number.
1-b . Solve these multiplications of integers.
  Esta unidad interactiva requiere la máquina virtual de Java J2RE.

Type the result of each operation. After typing a number you must hit Enter.
When you type the right number it will appear in the window. If the typed number is not correct it will not appear.

When you click on Init a new number will appear.

 
  Esta unidad interactiva requiere la máquina virtual de Java J2RE.

The numbers below are the results of these multiplications. Place them in their corresponding position.
         
           
  Eduardo Barbero Corral
 
Spanish Ministry of Education. Year 2007
 
 


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