To add integers with the same sign, add the absolute values of the integers and use the sign of the integers for the sum.

Adding integers with the same sign - Examples

Example 1 :

Add : (-2) + (-5)

Solution :

Step 1 :

Find the absolute values.

|-2| = 2 and |-5| = 7

Step 2 :

Find the sum of the absolute values :

2 + 5 = 7

Step 3 :

Use the sign of the integers to write the sum.

(-2) + (-5) = -7

Example 2 :

Add : (+2) + (+3)

Solution :

Step 1 :

Find the absolute values.

|+2| = 2 and |+3| = 3

Step 2 :

Find the sum of the absolute values :

2 + 3 = 5

Step 3 :

Use the sign of the integers to write the sum.

(+2) + (+3) = +5

Example 3 :

Use model to find the sum of "-4 and "-3"

Solution :

Let us take four negative counters for "-4" and three negative counters in the second row for "-3".

In the above figure, we find six negative counters in total.

So, the answer is -6.

Hence, (-4) + (-2) = -6

Example 4 :

The temperature was 2°F below zero. The temperature drops by 5°F. What is the temperature now ?

Solution :

Step 1 :

According to the question, the initial temperature was 2°F below zero. 2 below zero is "-2".

So, the initial temperature is -2°F

Step 2 :

Let us mark the initial temperature on the number line.

Step 3 :

A drop in temperature of 5° is like adding -5° to the temperature.

Since the temperature is dropping, we have to go below the initial temperature. The temperature drops by 5°. So, we have to count 5 units on the number line below -2 to find the final temperature.

That is "-7".

Mark the temperature now on the number line.

Step 4 :

From the above figure, the final temperature is -7°.

Justify and Evaluate :

In the above example, we have just added -2 and -5.

From the above example problem, it is clear that when we add two negative numbers, we have to add them as usual and take negative sign to the result.

After having gone through the stuff given above, we hope that the students would have understood "How to add integers with the same sign".

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