The Number Line
- Draw a line.
- Mark a point on it.
- Label it 0.
- Mark a second point to the right of 0.
- Label it 1.
The distance between these points labelled as 0 and 1 is called unit distance. On this line, mark a point to the right of 1 and at unit distance from 1 and label it 2. In this way go on labelling points at unit distances as 3, 4, 5, on the line. You can go to any whole number on the right in this manner. Below given is a number line for the whole numbers.
What is the distance between the points 2 and 4? Certainly, it is 2 units.
1) Addition on the number line
Addition of whole numbers can be shown on the number line. Let us see the addition of 3 and 4.
- Start from 3.
- Since we add 4 to this number so we make 4 jumps to the right;
- from 3 to 4, 4 to 5, 5 to 6 and 6 to 7 as shown above.
- The tip of the last arrow in the fourth jump is at 7.
- The sum of 3 and 4 is 7, i.e. 3 + 4 = 7.
2) Subtraction on the number line
The subtraction of two whole numbers can also be shown on the number line. Let us find 7 – 5.
- Start from 7.
- Since 5 is being subtracted, so move towards left with 1 jump of 1 unit.
- Make 5 such jumps. We reach the point 2. We get 7 – 5 = 2.
3) Multiplication on the number line
We now see the multiplication of whole numbers on the number line. Let us find 4 × 3.
Start from 0, move 3 units at a time to the right, make such 4 moves.
Where do you reach? You will reach 12. So, we say, 3 × 4 = 12.