Subtraction of Numbers Using a Number Line (Definition, Types and Examples) - BYJUS

Subtraction of Numbers Using a Number Line

A number line helps us visualize the value and the position of a number with respect to other numbers. This helps us perform the subtraction of numbers quite easily. We started learning subtraction with small numbers by counting with our fingers. We can apply the same strategy here to subtract bigger numbers with the help of a number line....Read MoreRead Less

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Subtraction of Numbers Using a Number Line

A number line is a representation of numbers on a straight line. It can be used to mark and map out numbers that are thought about when a question is presented. Number lines are important and are required because they help us see and understand different mathematical operations like addition and subtraction.






A number line never ends. It goes on till infinity. As you move towards the left of the number line, the value decreases, and as you move towards the right, the value of the numbers increase. Counting back from ten to one and even one hundred to one is something we all know by now. Now, we will look at what counting back by hundreds looks like.




When counting back by hundreds or tens, the difference in space between the values should also be shown on a number line.




We can start with an open number line. An open number line is a number line with no markings. It is usually used to map out the different possibilities of a given question. Take a look at the question provided below. 

Alex has 30 candies, of which he gave 10 to Cindy. Represent the remaining number of candies he has with him.

Alex has 30 candies, and 10 candies were given to Cindy. This means that we need to find the difference between 30 and 10.




So, this is what the number of candies looks like on a number line. The answer to the question is 20 candies.

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Solved Examples

Example 1: Represent 900 – 550 on the number line.




First, we reduce 500 from 900, and then, we will reduce 50.











So, the answer we get is 350, as shown on the number line.


Example 2: Jason and Tina were walking along a pathway next to a pond. Jason covered 600 tiles in one hour and Tina covered 480 tiles in the same time. What is the difference between the number of tiles both of them covered while taking the walk in the park?










So, we first reduce 100 four times from 600, followed by 80 units, and we get the result as:

600 – 480 = 120

And this is the result of 600-480, which is 120.


Example 3: Jenny has a box filled with her favorite books. She plans to give away some of them. There are a total of 10 books, of which she gives 3 to Sam, and 4 to Lily. How many books does Jenny have now?




The total number of books Jenny has = 10.




The total number of books taken by Sam and Lily = 3 + 4 = 7.

To find the number of books that are remaining, we need to reduce the books taken by Sam and Lily from the total number of books Jenny has, which is 10.




Therefore, the answer we are looking for is 3. The number of books Jenny is left with is three.


Example 4: A factory produces around 300 T-shirts. 50 of them were damaged because of a malfunctioning piece of machinery. 150 of these T-shirts were sent to stores across the world. How many T-shirts are remaining from the total number?



Since the company created 300 hundred T-shirts in total, this is what it looks like on a number line.




Since 50 of them were damaged, we reduce 50 from the total number.





150 T-shirts were removed from the total number again. This leaves us with the following.






So, we have a total of 100 T-shirts remaining from the total number of T-shirts.

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Frequently Asked Questions

A number line is similar to the scale that we use for measurement, it has numbers placed at equal intervals on a straight line.

Since we have an infinite set of real numbers or integers, a number can continue, and it does not stop.