# ADD AND SUBTRACT INTEGERS USING COUNTERS

Add and subtract integers using counters :

We can use the following colored counters to model the sum of integers with different signs. ## Modeling sums of integers with different signs - Examples

Example 1 :

Find the sum of "-4 and "+3"

Solution :

Let us take four negative counters for "-4" and three positive counters for "+3". Cross out each negative counter for each positive counter. In the above figure, after having crossed out each negative counter for each positive counter, the result is one negative counter.

Hence, (-4) + (+3)  =  -1

Example 2 :

Find the sum of "+5 and "-2"

Solution :

Let us take five positive counters for "+5" and two negative counters for "-2". Cross out each positive counter for each negative counter. In the above figure, after having crossed out each positive counter for each negative counter, the result is three positive counters.

Hence, (+5) + (-2)  =  +3.

Example 3 :

Find the sum of "+4 and "-7"

Solution :

Let us take four positive counters for "+4" and seven negative counters for "-7". Cross out each positive counter for each negative counter. In the above figure, after having crossed out each positive counter for each negative counter, the result is three negative counters.

Hence, (+4) + (-7)  =  -3.

Example 4 :

Find the sum of "+2 and "-3"

Solution :

Let us take two positive counters for "+2" and three negative counters for "-3". Cross out each positive counter for each negative counter. In the above figure, after having crossed out each positive counter for each negative counter, the result is one negative counter.

Hence, (+2) + (-3)  =  -1.

Example 5 :

Find the sum of "-5 and "+2"

Solution :

Let us take five negative counters for "-5" and two positive counters for "+2". Cross out each negative counter for each positive counter. In the above figure, after having crossed out each negative counter for each positive counter, the result is three negative counters.