**Adding on a number line :**

We can add numbers with same sign or different signs using a number line.

In the given two numbers, if the second number is positive, we have to move in the positive direction on the number line.

In the given two numbers, if the second number is negative, we have to move in the negative direction on the number line.

**Question 1 : **

Add "3" and "2" using a number line.

**Answer : **

Here, the integers "3" and "2" are having the same sign. That is positive.

To find the sum of integers 3 and 2, we have to start at 3

Since the second number "2" is positive, we have to move 2 units in the positive direction as given in the picture below.

After having move 2 units in the positive direction, we are in the position of "5"

Hence, 3 + 2 = 5

**Question 2 : **

Add "3" and "-2" using a number line.

**Answer : **

Here, the integers "3" and "-2" are having different signs.

To find the sum of integers 3 and -2, we have to start at 3

Since the second number "-2" is negative, we have to move 2 units in the negative direction as given in the picture below.

After having move 2 units in the negative direction, we are in the position of "1"

Hence, 3 + (-2) = 1

**Question 3 : **

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

**Answer : **

**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.

**Question 4 : **

Suppose the temperature is -1 °F and drops by 3 °F. Explain how to use the number line to find the new temperature.

**Answer : **

Start at -1. Move 3 units in a negative direction to -4; the new temperature is -4 °F.

**Question 5 :**

How would using a number line to find the sum 2 + 5 be different from using a number line to find the sum -2 + (-5) ?

**Answer : **

Instead of starting at 2 and moving 5 units in a positive direction to get 7, you would start at -2, move 5 units in a negative direction, and get -7.

**Question 6 : **

What are two other negative integers that have the same sum as - 2 and - 5 ?

**Answer :**

Sample answer: - 3 and - 4

After having gone through the stuff given above, we hope that the students would have understood "Adding on a number line".

Apart from the stuff given above, if you want to know more about "Adding on a number line", please click here

Apart from the stuff given in this section, if you need any other stuff in math, please use our google custom search here.

HTML Comment Box is loading comments...

**WORD PROBLEMS**

**HCF and LCM word problems**

**Word problems on simple equations **

**Word problems on linear equations **

**Word problems on quadratic equations**

**Area and perimeter word problems**

**Word problems on direct variation and inverse variation **

**Word problems on comparing rates**

**Converting customary units word problems **

**Converting metric units word problems**

**Word problems on simple interest**

**Word problems on compound interest**

**Word problems on types of angles **

**Complementary and supplementary angles word problems**

**Markup and markdown word problems **

**Word problems on mixed fractrions**

**One step equation word problems**

**Linear inequalities word problems**

**Ratio and proportion word problems**

**Word problems on sets and venn diagrams**

**Pythagorean theorem word problems**

**Percent of a number word problems**

**Word problems on constant speed**

**Word problems on average speed **

**Word problems on sum of the angles of a triangle is 180 degree**

**OTHER TOPICS **

**Time, speed and distance shortcuts**

**Ratio and proportion shortcuts**

**Domain and range of rational functions**

**Domain and range of rational functions with holes**

**Graphing rational functions with holes**

**Converting repeating decimals in to fractions**

**Decimal representation of rational numbers**

**Finding square root using long division**

**L.C.M method to solve time and work problems**

**Translating the word problems in to algebraic expressions**

**Remainder when 2 power 256 is divided by 17**

**Remainder when 17 power 23 is divided by 16**

**Sum of all three digit numbers divisible by 6**

**Sum of all three digit numbers divisible by 7**

**Sum of all three digit numbers divisible by 8**

**Sum of all three digit numbers formed using 1, 3, 4**

**Sum of all three four digit numbers formed with non zero digits**