Solution:
The reason is that it helps you to deal in which direction you have to move either on right or left of number line of that number.
Let me illustrate this by considering few examples.
1. 5 + 3 , here greater number is 5, so to add 3 you have to move 3 units right on number 5.
2. 5 + (-8), Greater number 8 , but it has negative sign before it . So to add 5 move 5 units left of 8, on number line.
