The Number Line

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Topic Content:

Meaning of Number Line
🏆 Number Line Check
Final Evaluation

A number line is a pictorial representation of numbers on a straight line. It is used to compare and order numbers.

Many of the numbers we use represent situations, which have direction as well as size. The numbers which have direction and size are called directed numbers.

Once a direction is chosen as positive +, the opposite direction is taken as negative –.

Looking at the number line, you will observe that the numbers increase in value as you move from left to right of the scale.

For example:

-5 is to the right of -6, so -5 is greater than -6. This means that -6 is less than -5.

Mathematically, the symbols ‘>’ and ‘<’ are used for greater than and less than, respectively.

> Means ‘is greater than’ i.e. -5 > -6

< means “is less than”, i.e. -6 < -5.

Similarly, on the number line.

-2 is to the right of -4, so -2 > -4 or -4 < – 2.

3 is to the right of -1. So 3 > -1 or -1 < 3.

8 is on the right of -7, so 8 > -7 or -7 < 8.

Note: On a number line, a number to the right is always greater than a number to the left.

Worked Example 10.1.1:

Arrange these numbers in ascending order:

5, -6, -4, -10, -19, 7, -13, 21 and 14

Solution

Ascending order means from smallest to largest.

-19, -13, -10, -6, -4, 5, 7, 14.

Hint: Note that the largest number with a negative sign is the smallest number, and the largest number with a positive sign is the largest number.

Worked Example 10.1.2:

Arrange these numbers in descending order:

-3, 1, -5, 10, 6, -7 and 3.

Solution

Descending order means from largest to smallest:

10, 6, 3, 1, -3, -5, and -7.

Worked Example 10.1.3:

Arrange these numbers in ascending order:

-8, 0, -12, 7, -5, 4, 20, 1.

Solution

-12, -8, -5, 0, 1, 4, 7, 20.

🎯 JSS1 Arcade 10-question challenge

🏆 Number Line Check

Pick the correct answer as fast as you can.

Pass Mark 70%

Final Evaluation:

1. Arrange these numbers in ascending order: -5, 3, -8, 0, 7

2. Arrange these numbers in descending order: 4, -2, 8, -6, 1

3. Arrange these numbers in ascending order: -10, -3, 5, 0, -7

4. Arrange these numbers in descending order: -4, 9, 2, -1, 6

5. Arrange these numbers in ascending order: 12, -5, 0, -9, 4

JSS1: MATHEMATICS - 1ST TERM

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