Adding integers

Adding integers

 Adding integers is different from adding whole numbers. Signs of numbers are important factor in adding integers. There are two rules that we need to follow in adding integers

 

 

 

Rule No. 1:

• To add integers having the same signs, add the numbers and copy the common sign to the sum.

Illustrative Examples 

 1. (+13)   +  (+34)  = 

 Solution:          

 +1 3             

  + +3 4         

 +4 7 The sum is +47 or 47 since the common sign is positive (+). 

Examples

 2. (-411)  +  (-234)  =

  Solution:  

             1     

    -4 1 1  

         + -2 3 9     

    -6 5 0   The sum is -650 since the common sign is negative (-).

 

Multiple Choice

Answer the following:

1. (-67) + (-24)=

• -91

• -43

• +91

• +43

Multiple Choice

2. (+45) + (+98) =

• +53

• +143

• -53

• -143

Rule No. 2:

• To add integers having different signs, disregard first the signs and subtract the numbers. Then, copy the sign of the greater number to the final answer. (Note: Disregard also the sign in identifying the greater number.)  

Illustrative Example 

 

 

 1. (-56)   +  (+24)  =  

Solution: 

 

             (-5 6)

    + (+2 4)         

       -3 2    The final answer is -32. The sign is negative (-) since  the sign of the greater number which is 56 is negative.  

Multiple Choice

Answer the following:

1. (-89) + (+24)=

• -65

• -78

• +65

• +78

Multiple Choice

2. (+75) + (-13) =

• - 28

• -62

• +65

• +62

Multiple Choice

Answer the following:

1. (-89) + (+24)=

• -65

• -78

• +65

• +78