What is a Number Line?
A number line is a straight line consisting of numbers that are positioned at equal intervals in a chronological order. The number line is expressed horizontally and can be extended infinitely.
On the number line, the numbers increase when we move from left to right and decrease when we move in the opposite direction.
An example of a number line for whole numbers is shown in the image. Here, the number line includes both positive and negative numbers.
As you can see, zero is the middle point of the number line, while the numbers on the left side of the zero are called ‘negative numbers’ and the numbers on the right side of the zero are known as ‘positive numbers’.
In a similar manner, the numbers on the right of the zero are greater than the numbers on the left of it.
Representing Fractions and Decimals on a Number Line
Along with whole numbers and natural numbers, other forms of numbers can also be represented on a number line. Fractions and decimals can be represented on a number line as well.
On the number line in the image, both fractions and decimals are represented. The fractions and decimals on the left hand side are less than the fractions and decimals on the right hand side.
Solved Examples Using Number Line
Example 1:
On a number line, Jack starts at zero and jumps five units ahead. Where will he land after making three jumps?
Solution:
The first jump will bring Jack to position 5 on the number line. He will land on the number line at 10 after the second jump and at 15 after the third. The following number line can be used to illustrate this.
Hence, after making three jumps, Jack will land on 15.
Example 2:
Use a number line to calculate 8 + 4.
Solution:
We can solve this sum using a number line. Since we have to add, we will start counting from 8 for the next four intervals.
Thus, 8 + 4 will give us 12.
Example 3:
Out of 25 students, 7 are going on a field trip. Using a number line, can you find out how many students stayed back?
Solution:
Total number of students = 25
Number of students who went on the field trip = 7
In order to find the number of students who stayed back, we have to use the subtraction method. We can do that with the help of a number line.
By counting backwards from 25 for seven units, the result is 18.
Hence, 18 students stayed back.
The number line can be used to perform the four fundamental arithmetic operations of addition, subtraction, multiplication, and division.
In addition and multiplication, we move to the right side of the number line, while for subtraction, we move to the left side of the number line.
To perform the addition operation on a number line, we skip count and move forward (towards the right) to the designated number on the number line.
To perform subtraction operations on a number line, we skip count and move backward (towards the left) to the designated number on the number line.