The Number Line

We 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 labelling points at unit distances as 3, 4, 5,... on the line. We can go to any whole number on the right in this manner. This is a number line for the whole numbers.

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.

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.

Multiplication on the number line 
    We now see the multiplication of whole numbers on the number line. Let us find 4 × 3.